Fuel Management

Gas vs. Diesel: The Bad Investment Only Fleet Managers Know About

October 2015, Government Fleet - Feature

by Bob Stanton

Gas versus diesel is a contentious topic. One fleet manager shares his reasoning when making the unpopular decision to spec for gasoline engines. File photo
Gas versus diesel is a contentious topic. One fleet manager shares his reasoning when making the unpopular decision to spec for gasoline engines. File photo

Fifteen years ago, as the fleet management director for Polk County, Fla., I chose to avoid specifying diesel engines in Class 3-6 trucks. At that time, the decision that any vehicle with a gross vehicle weight rating of 19,500 lbs. or lower purchased by Polk County would be powered by gasoline engines only became instantly unpopular. That decision was supported by solid data including a detailed analysis of Polk County’s diesel versus gasoline operating experience that clearly illustrated gasoline engines were a better investment (see “Why Polk County Switched From Diesel to Gasoline Power,” from the March 2000 issue of Automotive Fleet magazine).

At A Glance

Fleet managers can defend the purchase of gasoline Class 3-6 vehicles by:

  • Comparing acquisition costs with diesel vehicles
  • Showing that diesel fuel's higher cost per gallon negates its slight advantage in fuel economy 
  • Calculating accurate resale value of both types of vehicles
  • Knowing how long vehicles are kept in service and their applications.

A lot has happened to engine technology in 15 years, so it’s time to re-evaluate the data. Has the tide turned in favor of the diesel engine, or does emotion, chutzpah, and the virile attraction of “more power” still drive the diesel decision?

Arguing for Gasoline Vehicles

Fleet managers, the subject matter experts in this area, have a responsibility to ensure tax dollars are spent wisely to maximize the value of every vehicle investment. The fleet manager’s role in the specification process is to ensure every vehicle meets the needs of the mission for which it’s intended and that expenditures are based on fact, readiness, and capability rather than emotion and appetite.

Oftentimes, departments seize the vehicle acquisition season as an opportunity to overreach in vehicle specification demands, driving up costs with little or no compelling justification. The most egregious of these may be the demand for diesel power. In some entities, departments with more clout than their fleet department are seldom challenged effectively enough in this area.

This article provides fleet managers counterpoint arguments they can use to facilitate a more reasoned debate over this decision and help ensure that taxpayers’ investments are better protected by a more deliberate discussion. The same methodology used 15 years ago was used for this analysis, including updated calculations and current operational history.

Miles Per Gallon

Although diesel engines enjoy a sizeable miles per gallon (mpg) advantage over gasoline engines in automobiles, truck engines are a different story. The actual advantage enjoyed by diesel engines in light and medium trucks is less than 2 mpg. In government fleets where daily travel distances are limited, idling is an unfortunate reality, and load requirements can be met equally well with gasoline or diesel engines with little or no impact on mpg; diesel fuel’s higher cost per gallon actually negates its slight advantage in mpg.

Maintenance Costs

Non-fleet “experts” tout that rigid construction and the lack of spark ignition make diesel engines cheaper to maintain than gasoline engines. Fleet managers and maintenance personnel know better. Maintaining diesel engines is made more costly than gasoline engine maintenance by routine maintenance costs and frequency, higher diesel engine hard parts cost (starters, alternators, water pumps, batteries, etc.), selective catalytic reduction (SCR) emission system maintenance and repair, turbocharger maintenance, and other factors not present in gasoline engines. Although no hard data exists, some fleet managers say that diesel vehicles average 2.5 to 4.5 more downtime days per year. This is primarily due to either the lack of parts availability or to a shortage of qualified technicians, either at the dealership or fleet level.


Diesel engines last longer. That’s certainly true for over-the-road semi tractors that typically travel 80,000 to 100,000 miles per year. These vehicles are typically expected to operate for half a million miles or more before trade-in or sale. In the past 15 years, at least nine light- and medium-duty diesel iterations have been introduced to the marketplace by Ford, GM, and Fiat Chrysler Automobiles (FCA). Engine families have been rendered obsolete either due to emission control regulations or, in some cases, their own inherent mechanical shortcomings. Few engines in the light/medium class have been around long enough and in great enough numbers to support the longevity claim.

And for government fleets, who really cares about longevity? Government fleets seldom if ever retain a Class 3-6 vehicle longer than eight or 10 years, or for more than 125,000 miles. Further, few governments apply a longer life expectancy to light- and medium-duty diesel vehicles than they apply to gasoline vehicles of similar size. Diesel vehicle longevity is a non-factor in government fleets as both gasoline and diesel vehicles are typically replaced on identical life cycles.


The belief that diesel vehicles pull better is partially true. Gasoline engines usually have the edge in horsepower, while diesels typically offer higher torque. But in a government fleet application, these attributes are similar in significance to the longevity claim because they don’t matter either. The short-term torque required for government fleet applications, even in severe duty, can be met equally well by a gasoline or diesel engine; gasoline is simply less expensive to purchase and maintain.

Acquisition Cost

This is an often overlooked aspect in the government fleet acquisition dialogue because by the time the narrative extends to the acquisition cost, the operating department has successfully made its case for diesel, and the gasoline alternative is off the table. Fifteen years ago, the government premium paid for the diesel option ranged from $2,200 to $3,000. Today, that premium has risen to about $8,000. How can a department quantify a benefit large enough to justify paying that premium for a diesel engine when an equally capable vehicle can be purchased for less?

Resale Values

Diesel vehicles have higher resale values. The market has realized the value of diesel light and medium trucks, and auction proceed statistics clearly reflect this advantage.

Fleet managers should always consider resale value when purchasing vehicles, but they should be cautious when evaluating the benefit of this advantage. It’s not enough just to target recovering the original acquisition premium at the auction eight to 10 years in the future. Fleet managers who recognize the time value of money understand the implications and responsibility for recovering this premium in real-time dollars. At 3%, in order to recover a $7,800 diesel premium paid originally, fleets and finance departments recognize the premium actually represents more than $9,500 in future value, an auction premium target that’s non-existent when selling gasoline-­powered trucks.

What the Studies Say

A widely quoted 2013 study comparing the total cost of ownership (TCO) between gasoline- and diesel-powered vehicles conducted by the University of Michigan Transportation Research Institute concludes that owners of diesel vehicles enjoy a cost advantage over owners of gasoline vehicles. However, the study was heavily slanted toward diesel automobiles from Volkswagen and Mercedes and only covered the first three to five years of ownership, when diesel resale values enjoy a decidedly higher advantage. The study’s conclusions for trucks include the following:

“Vehicles in the medium-size pickup segment have a mixed picture of TCO in the three-year timeframe. The Chevrolet Silverado 2500 saves the owner $3,673 more than the owner of the gas-powered version of the vehicle and the GMC Sierra 2500 owner saves $2,720. The Dodge Ram diesel owner saves only $67 more than the owner of the gas-powered version. The F-250 diesel owner pays an estimated $1,395 more than the owner of the gas-powered version,” the study stated.

It should be noted that this study compared vehicle costs operated by ­consumers rather than vehicles operated in commercial/­fleet related service.

Another well-known and often-quoted source of vehicle cost data is Vincentric. In a 2012 study comparing gasoline vs. diesel vehicles, the company found: “When all costs to own and operate a diesel were taken into account, the average cost of ownership for diesels was $1,203 more than their all-gasoline-powered counterparts, with results assuming an annual mileage of 15,000 over five years.”

These findings were largely unchanged in the company’s follow-on study in 2014.

Ensure the Best Purchase

As new diesel engine families enter the marketplace such as the new 3L available in the Ram 1500 and the 2.9L Duramax soon to be available in the Chevrolet Colorado/GMC Canyon, it will be interesting to watch how these entries affect government buying patterns. Because these entries are not targeted specifically for the medium-duty segment where power is perceived as being only available from diesel engines, they may never enter the government “mainstream” but may instead be used as niche units utilized in limited quantities, unlike their larger 5L and 6L counterparts.

There will always be solid and perfectly acceptable reasons to select and justify diesel engines in government vehicle applications. For instance, diesel fuel may be a safer choice than gasoline for an off-road fire truck (e.g. brush truck) should refueling at a fire scene be needed.

It’s up to the fleet manager, in conjunction with peer discussions and reasoned consideration, to be the voice of reason in the sometimes highly charged specification process. As the subject matter expert, the fleet manager has a responsibility to ensure the best, most capable and cost-effective vehicles are selected, in spite of the wishes and pressure from outside. The fleet manager is the last line of defense in ensuring taxpayers’ vehicle investments are reasonable and represent the best value and return.

Most fleet managers agree the diesel engine option is a less-than-optimal choice and a bad long-term investment. Their role in the specification process is to defend this position from strength with data and commitment.

Bob Stanton, CPM, CPFP, is an independent fleet consultant and retired public sector fleet manager with 39 years of experience.


  1. 1. Mike Moser [ October 19, 2015 @ 12:50PM ]

    Great article, Bob! The school bus industry is moving away from diesel power and toward gas and propane, with much of the savings achieved from lower maintenance costs. In that arena, short warm-up time and quieter operations are also substantial benefits. Personally, I like the idea of cleaner burning propane near the air our kids are breathing.

  2. 2. Mark Stinson [ October 20, 2015 @ 05:36AM ]

    I also agree this is a great article, I constantly fight with preconceived notions that diesel is a better fit and will work better, but we see a tremendous increase in down time for repairs and maintenance due to large amounts of idle time. Thanks for bringing this information forward.

  3. 3. Rick Davenport [ October 20, 2015 @ 06:06AM ]

    About five years ago I made the switch to purchasing gasoline engines for light and medium duty except for 4 GM pick-up trucks as a test. We are not the only ones who have realized the benefits of Diesel over gasoline have gone away with the implementation of complex and engine damaging emission control systems. As a result of increased demand Ford is now offering a V10 gasoline in class 7 trucks.
    Great article, it lays out my point view better then I would have.

  4. 4. Phil D'Hondt [ November 02, 2015 @ 04:03PM ]

    Good article, confirmed my thoughts on diesel. My one question is - this article is oriented towards govt. type usage, with controlled parameters for mileage before selling. We are a private firm who works our vehicles very hard and maintains and keeps them in good shape for an extended period of time. 20,000 to 50,000 miles / year is normal and we keep the vehicles for at least 5 years and longer if possible. Do you have any longer term data based on higher mileage per vehicle?

  5. 5. Robert Baker [ November 05, 2015 @ 11:50PM ]

    The advantages of diesel powered light to medium trucks went away over 10 years ago. It is unfortunate that Ford doesn't offer a V-10 in their F-350 and F-450 pick-up trucks which would be a cost savings for the end user if they are towing up to 18,000 lbs. as they offer in the cab chassis F-450. If you spec a diesel in a cab chassis in a F-450 the towing and payload is virtually the same compared to the gas V-10. But you save $8K up front over the diesel. My belief is that if you are regularly towing up to 31,000 you should be in a Class 6 or 7 truck (Ford F650/750) in which truck is better fit for handling that much weight with the frame, suspension, brakes and etc. along with you can get a gas V-10 in that application. Another point to consider is the after warranty repair costs when it comes to diesel engine repairs, especially with some trucks (Ford F250-F550) you have to remove the cab when it comes to working on the rear of the engine or replacing the engine. The garages that I managed are not equipped to be removing a cab off of a truck and why would I want a vehicle that has the potential to create so much downtime when the engine is in need of major repairs as we keep our vehicles 10 plus years. It reminds me of the early Ferraris that you had to remove the engine every 30K miles to do a major service which is probably acceptable for an occasional driver which is increasing in value (as long as the vehicle is in great condition) but not for a commercial truck that needed to get work done and you have to watch your (TCO).

  6. 6. Brue Ottogalli [ November 13, 2015 @ 10:30AM ]

    Great article Bob. It's like you read my mind, almost everything you wrote about I've been telling people for years. I just can't justify purchasing diesel engines for an additional 10K when all of my fleet does is idle all day. I'm currently in the process of replacing 12 F-650 diesels with the new gas engine.

  7. 7. Robert Owen [ November 16, 2015 @ 08:01AM ]

    While you certainly have to consider the job the truck will be doing before deciding gas or diesel, we for the most part get diesel for the trucks that work all day (1 ton and up) and gas for those that get you out to a job site for the day (1/2 and 3/4 ton).
    We also have a policy against idling that is enforced so that is not an issue. The replacement schedule for gas is 10 years and for diesel is 15 years. It is common to have over 200,000 miles when they are sold at auction.

  8. 8. Cliff Downing [ November 17, 2015 @ 10:16AM ]

    Great read, and I concur with the analysis. My reasoning for going with gas over diesel in a 2015 2500HD Silverado was based on this same analysis. Diesel is nice, but gas was more cost effective and is more than ample for my needs. I haul more than tow, so the gas motor is more than enough for the task.

  9. 9. Bob Stanton [ November 20, 2015 @ 03:05PM ]

    In reply to Phil D'Hondt:

    Government applications are less controlled than you may recognize. While some applications operate within confined geography such as within city limits, other applications are located within large counties, some of which are larger than some states (e.g. Polk County, Fl. & El Paso County, Co.). Further, while your own targeted retention is 5 years, governments typically retain vehicles far longer, 8 - 10 years is routine. While your application may accumulate miles faster than a typical government, public sector vehicles will routinely accumulate over 100,000 miles; our applications may not be that different from yours. You didn't mention if trailers are utilized in your application; trailer usage is routine in many government truck applications with the attendant wear and tear characteristics expected in more severe duty usage.

    As to high mileage data, please understand the latest generations of diesel engines in light and medium duty applications are only 3 - 4 years old; long term, high mileage data is yet to be broadly attained. This is particularly true of the long term integrity of the SCR emission system. Regen cycles, DPF longevity and their long term upstream effects on engine health are all yet to be determined. Nevertheless, gasoline engine maintenance will be continue to trump its diesel counterparts and, given current the overall cost of ownership of the two, my calculations say a user can replace the gasoline engine twice (long block) over the life of an extreme 250,000 mile vehicle retention cycle and still come out ahead.

  10. 10. Bob Stanton [ November 21, 2015 @ 08:17AM ]

    In reply to Robert Baker

    Thank you for your comments; I failed to mention the removal of the cab requirement for certain Ford diesel repairs and I'm glad you did. I suspect Ford doesn't make the 6.8L available in the pickup application because the weight distribution in heavy towing as you mentioned would/could compromise overall stability. There wouldn't be sufficient weight behind the cab to the hitch thus compromising the tongue weight. Thanks for taking the time to share your experience.

  11. 11. Ryan Coomes [ January 05, 2016 @ 03:08PM ]

    Great article, and I have to agree that gas is the way to go. With my farming operation we drive 3/4 ton gas pickups while a lot of other farmers drive diesels. The higher upfront cost keeps me away from them not to mention it is like maintaining another tractor for the farmers that drive them.

  12. 12. Bill [ March 22, 2016 @ 04:32PM ]

    Thank you for the article. I am an owner of an automotive shop focusing on medium/light duty trucks. We continually have diesel trucks pull into our shop with over 3, 4 and 500k miles on the odometer. I have seen a couple gas trucks over 300k, but no where near 400k. The biggest killers of diesels are neglecting maintenance. I have worked with clients for years, educating them on how to maintain their truck and it makes all the difference.

  13. 13. Tyler [ March 29, 2016 @ 11:55AM ]

    I agree on some points, but when comparing the pulling power and torque of a current-gen diesel to the top current-gen gas offerings, there is simply a vast difference. For pulling heavy loads, the diesel is far superior, especially in hilly terrain, and very much better at high altitudes. Part of the problem is the lack of quality gasoline engines - the OEMs seem to offer "neutered" engines for commercial use in order to push the diesels. Ford's V10 is the only offering which is semi-adequate, but when you discuss pulling 18k pounds, I can only begin to fathom the torture that would be in the mountains with a gas engine.

    I also disagree on fuel economy, especially when loaded or towing. Gasoline engines seem to suffer far more in terms of mpg when they are worked hard. Diesel engines have much more torque, in some cases twice the torque, all available at low RPM.

    The biggest disadvantage of the modern diesel is the complex and expensive emissions control system. It has added thousands in cost to the engine option, and contributes greatly to the problems modern diesels suffer.

    I will say gas engines can idle all day long without much issue.

  14. 14. Joe Roe [ May 16, 2016 @ 07:50AM ]

    I drive a Dodge Ram 2500 Cummins, it's a farm truck, that averages 21.5 mpg hwy and a Volkswagen Golf TDI that averages 44mpg combined. I also have a frugal diesel John Deere tractor. After careful analysis and and consideration, diesels are still more cost effective. Better fuel economy per foot pound of torque wins. I've got over 200,000 miles out of both the car and the truck. Just checked the compression, no signs of letting up. At the rate the engines should last at least 500,000 miles per vehicle with routine maintenance. Whether I'm pulling a tandem axle trailer or driving coast to coast. I'm thankful to get better fuel economy with my diesels. Are they slower to accelerate, sure, less RPM. Can they pull more, sure, longer and stronger connecting rods. Do they get better fuel economy, sure, less fuel injected per cycle, fuel not dependent on air ratios. More air the better.


  15. 15. Beefey [ May 16, 2016 @ 09:40PM ]

    Thanks for the comment Joe-- You're an idiot.

    Everything you stated is a harsh generalization. Bob actually did the legwork with real statistics on this so you can blast the case with "stronger connecting rods"?!? Is that the best you got?

    In terms of fuel economy per ft-lb of torque I'd say your JD kicks your trucks ass. So does that mean you'll be pulling your bobcat trailer with that now?

    The point of the article is perhaps the fleet doesn't need a 1000ft-lb truck to trim the trees.

  16. 16. Ed-Ro [ May 18, 2016 @ 08:59AM ]

    Having lived in Pinellas cty, we were virtual neighbors. In my own career, I've had to live with "fleet mentality". After many years of offering solutions to improve productivity, I come to realize that the fleet managers, only real concern is to spec out vehicles as cheaply as possible. For example, there is a large and well known delivery company with thousands of units, which does not equip their trucks with A/C, despite numerous studies concerning driver comfort, which as you know is a large concern in the trucking industry. The reason is simple, it costs money. Too bad for the drivers who are forced to sweat it out during August in Florida!
    Selecting a gas engine over diesel is yet another way to cut acquisition costs. The studies you cited, does not tell the entire story. Fuel economy, maintenance costs, longevity, torque and horsepower, resale are the advantages of diesel. The difference between the fuels is simple physics. Diesel has more energy density than gasoline, and therefore, will release more power and provide more fuel economy from every gallon of fuel. You make it a point to state that between gas vs diesel, the economy is close to similar. But overall diesels get better fuel economy. OTR fleets understand the importance of fleet wide fuel economy. Even an increase of .01 savings in fuel, fleet wide, can result in an annual savings worth thousands of dollars. (Depending on the number of units, of course) A 1-2 mpg advantage over a year could potentially save enough to buy a couple of additional trucks! The small difference that you dismiss between gas vs diesel fuel economy is huge for an entire fleet!
    Horsepower is a mathematical figure derived from torque and rpm. (TQ X RPM / 5252) Based on this, you can have high horsepower, with a little torque, if you can spin the engine fast enough. But really? Is that the best way to pull around a fully loaded truck? For a gas engine to pull a heavy load, having less torque, it needs to spin at a faster rpm. This higher engine speed in gas engines, results in more wear, creates more heat and burns more fuel. The increased heat and wear requires increased maintenance. The argument that diesel costs more to maintain isn't true when you consider heavy duty use. It's simple to understand, gas engines have to work harder to get the load moving. It burns more fuel to do it and it requires more maintenance because of it. This is why gas engines in the heaviest vehicles were dropped long ago. On the flip side of the coin. Diesels produce much more torque and they do it at low rpm. This means less wear, less heat buildup, and less stress. Further these engines were designed to work. The metal used is denser, the components are stronger, they have large capacity oil and coolant reservoirs built right in. All of these things adds to their service life expectancy and longevity. Cummins, for example has a 300K service life expectancy. There isn't a gas engine out there that can come close, under similar work conditions. In your article, you state that fleets do not keep their vehicles for long, so by implication, longevity isn't an advantage worth the added cost. I beg to differ. Diesel engines will last longer because they are designed for the long haul, but it also means that they are more durable in the short term as well. With a more durable build, they are less likely to fail. Finally, I'll address resale. Although you agree that diesels tend to have a higher resale value than their gas engines counterparts, it can be worse that that. Due to the greater wear and tear that gas engine equipped vehicles experience, many fleets end up just junking their trucks all together at the end of their service. This means that there is no resale or return on investment at all. OTOH, you'll typically get more back on the sale of a diesel equipped vehicle, that you can now turn around and invest back into new equipment.
    No matter the advantages are, which the more expensive equipment offers, the bottom line is simple. Fleet management is instructed to spend as little as possible on large initial purchases without considering the costs down the line. It's easy to understand. it's easier to justify saving money on a large initial purchase, than to forecast how much additional money that investment will require to maintain and operate it. For the most part, Fleet managers do not live with the equipment that they purchase, nor do they care, so long as it can be used. They follow a policy. Many aren't even familiar with the equipment they purchase, so long as it meets the bottom dollar. If they can get away with putting a tiny four cylinder in a big truck, because it costs less up front and despite how much harder it has to perform, and the losses to production of the employees who depend on the equipment, they would do it.


  17. 17. Roy [ June 06, 2016 @ 10:17AM ]

    Your article is spot-on Bob. There was a time when diesel engines made sense in a light-duty fleet application. As you point out, when the upcharge was minimal, repair costs were reasonable, and we saw a return at auction, diesel was a viable option. When EPA requirements drove up the initial cost, maintenance & operating costs, and the repair costs, that changed. Any of us who have sizeable fleets with light, medium and heavy-duty diesels know how much the maintenance and repair costs have increased, along with the increase in downtime. Failed EGR valves and EGR coolers; plugged or cracked DPFs, the degradation of motor-oil caused by dilution from "doser" injectors and/or soot pumped into the crankcase by the EGR, and the resulting catastrophic failures... that was enough to convert me in 2012 to gas engines for our light-duty fleet. The only vehicles I have sent to auction in a non-running condition have been light-duty diesels that experienced catastrophic failures and weren't worth repairing. I personally own a diesel pickup, this is my fifth personal pickup with a diesel engine. It's my money, my time, my risk and my testosterone. But as a responsible fleet manager, I wouldn't be doing right by the taxpayers if I purchased diesel light-duty vehicles with their money.

    And Ed, I was the customer before I became the fleet manager. I am very familiar with the equipment and the customers' needs, one of which is reliable equipment that is standing by and ready. The gasoline-powered light-duty vehicles in our fleet are more reliable and less expensive to operate than diesel engines in like vehicles. We run the gasoline engines 120,000 - 150,000 trouble-free miles, with very few exceptions. I can't say the same for the light-duty diesels. The article is aimed at the light-duty segment. Of course we aren't going to put a gasoline engine in a 33,000 lb dump, or a 105,500 lb trash hauler.

    My responsibility to the customer is to provide them with a reliable, cost-effective fleet. That is exactly what I am doing by avoiding light-duty diesel engines. The proof is in the numbers, not in the rhetoric.

  18. 18. Ed-Ro [ June 20, 2016 @ 02:09PM ]

    Roy, I've been in the trucking industry for over 30 yrs, having worked long haul to local deliveries. From big 18 wheelers to pick up trucks, and to this day I still maintain a Class "A" license. I'm also a pretty accomplished mechanic, working with both gas and diesel. And like you, I also own gas and diesel vehicles. In my career, I've had to deal with numerous fleet managers even being involved in recommending equipment when needed. Some fleet managers are great people and they listen to the needs of the employees, while remaining within budget constraints so that their company can provide the best possible service to their customers. Others, all they cared about was the bottom dollar. This gas vs diesel debate is a prime example of the bottom dollar mentality of some fleet managers. The justification for cost using false information should be your first clue. Mr. Bob's article is not spot on. It is far from it. Example; he links a chart showing comparisons between gas vs diesel, however the chart reveals that the vehicles used were 3/4 ton pick-ups, not the type of commercial vehicle shown at the beginning of the article, which is a Ford F450 with a utility bed and a man lift. The chart shows two Ford gas engines. One a 5.8L and another, a 5L. Never mind the fact that both engines are currently out of production, but it's already hard to believe that either would provide 15mpg/16mpg in a 3/4 ton truck respectively. I seriously doubt that the commercial F450 with a current modern gas engine will get anywhere close to that fuel economy. The chart shows another interesting fact. When compared, the price of gas vs diesel is 30 cents. Keep in mind that prices often fluctuate and depending on what part of the country you buy fuel in, diesel is not always more expensive than gas. BTW, as of this writing, the difference in price between gas vs diesel in Polk county, where Mr. Bob worked, is 10 cents. In fact as of this writing premium gas is more expensive than diesel, in Polk cty. Next; Mr Bob makes several points of how diesel truck engines do not have that much of an advantage over gas in terms of fuel economy, stating that the difference is less than 2 mpg followed by the fact that gas is cheaper. I can tell you that in the world of over the road trucks. The avg fuel economy of an 18 wheeler is about 5MPG and for them it's a really big deal when they can save .05 MPG fleet wide. For the cheaper cost of the gas powered work truck which Mr Bob favors, he's certainly willing to spend more of the tax payer dollars on gasoline which is a price subject to wide fluctuations. BTW if you want to do the math, you will see that when fuel prices go up considerably, the diesel's greater fuel economy has a greater economical advantage. On a fleet wide basis a 2 MPG difference is HUGE!
    Now you, Mr Rob claim that you get 120K to 150K trouble free miles out of your trucks. In general, with current technology, you should be able to. 120K was considered a lot for a car back in the 1950s but today, it's routine. Even with this modern tech, diesels can run for twice this. The fact is, they were designed for work from the get-go. They have larger oil capacities, bigger cooling systems, bigger internal parts, and made of denser steels. In his article, Mr Bob fails to mention fuel economy, longevity, and maintenance under real world conditions. Under a load, the gas engine has to run faster, to create the horsepower to move the load. This is a fact of gas engines. It produces horsepower at higher engine RPM, whereas diesels operate at much slower engine RPMs. Faster RPM means more heat, Faster RPM means more wear and tear, Faster RPM means more fuel is burned, Faster means shorter longevity. The diesel makes tons of torque at low RPM. Theres less heat, less wear & tear, less fuel is burned and it has a longer service life. The gas engine with it's need to run quicker to make more horsepower means, it will require more maintenance. More frequent oil changes, more frequent tune-ups, more frequent flushes, etc. Those are the physical facts. If you're looking at oil capacity and arguing that it's cheaper to replace 5 qts of oil (for gas) vs 8 qts (for diesel) you're missing a huge maintenance picture. More oil capacity is better for your hard working engine. More oil means improved lubrication because it takes more time for the oil to become contaminated, more oil absorbs more heat, more oil helps your engine last longer. You mention that current diesels have suffered from EPA mandates which have reduced fuel economy, dependability, and increased operation costs. That part was true a few years ago when diesel engine manufacturers had to comply with these new regs. Keep in mind that gas engines also have to comply with EPA mandates. Back in the 70s when gas engines first had to meet CAFE standards, and emissions regulations, they suffered from the same types of problems current diesels were facing with emissions today. Poor fuel economy, poor power and performance, and higher operating costs were common. Today, gas engines are powerful, efficient and clean. New diesels are quickly getting past the emissions problems, just like gas engines did decades ago. A cost effective fleet isn't just saving money at one place, with the initial cost. It's the overall costs, from purchasing to operating costs. With a flucting fuel market and economic uncertainty, gambling that gas will always remain low and quick vehicle turn over is total folly. What if fuel prices skyrocket again and we're back to $4/gal? Your budget is drastically cut, so that you cannot acquire new vehicles and must hold onto the older trucks longer? Well, you're screwed and so your tax payers who count on you. Good fleet managers consider these things too.

  19. 19. Jake [ June 21, 2016 @ 03:00PM ]

    You stated that there is no return on their investment.... I stopped reading after that. I'm sorry for your loss.

  20. 20. RICHARD O. WALLACE [ July 05, 2016 @ 06:02PM ]

    Agree for the F-250/F350 types we use. The DEF brings up the fueling costs while diesel is usually more expensive than gas here too. NO advantage in fuel economy. The Particulate filters are going to be expensive to service, gas does not have that. Gas has had a few cat. problems yet it has been covered by Ford warranty--diesel particulate filters are on the City. Labor is horrendous with the 6.0, 6.4 and 6.7. Then we are continually having EGR cooler problems which tie up the units 2-3 days. We do cost downtime here too. None of our lighter fleet every goes to 120,000 miles, most are sold below 80,000. Simple back-of-envelope math says forget the diesels.

  21. 21. I was there [ July 10, 2016 @ 07:04PM ]

    Your also the same guy that thought putting recap tires on ambulances was a good idea.....we know how that worked out, several instances where ALS Ambulances were damaged and sitting on the side of the road waiting for another ambulance to take the patient the rest of the way to the hospital.

  22. 22. Ray Gassert [ July 18, 2016 @ 12:28PM ]

    Great article. I am in the midst of convincing some older school construction background guys that the acquisition costs now make diesels a poor choice for our needs. Ask them to a man, and they blurt out "DIESEL!" when the boss asks what we should buy but when I ask them how many miles they think it takes to make up the acquisition cost, they are off by about 250,000. And we're not towing or hauling anything but light tools and people. The needs do not back up the costs. We'll see if they listen....

  23. 23. Big Ed [ July 24, 2016 @ 10:27PM ]

    I am a veteran hot shot driver from Texas. I am done with diesels. Period. The firsts ones I had were good, like the Ford 7.3 and 1st Gen Cummins. Both on 1 ton chassis, no trailer pulling but heavy loads on flatbeds. The new late model diesels are problematic and more expensive to operate. This based on my checking account and not macho hype from coal rollers who delete the dpf and add a tuner. Too many trips to the dealer shelling out 2000 to 4500 dollars for repairs plus down time. I now drive a 2012 Ford f350 with a 6.2 gas. No major issues and I have 349,000 miles so far. No blowbye and same tranny. I use Mobil one oil and expect to double that 349,000 miles. Plus I can idle it all day and night with no issues unlike the newer diesels. Plus when the engine and trans. let go they will be replaced with salvage motor and tranny at low cost. Why buy a new truck? Bottom line, if your not towing real heavy, go gas!

  24. 24. Julio Figueroa [ August 11, 2016 @ 06:48AM ]


  25. 25. Jim Perry [ August 22, 2016 @ 12:14PM ]

    I think your way off Bob. It is more expensive to purchase Diesels upfront but with some notable advantages. First you have MPG, I have 2 trucks identical ones gas and the other diesel, the diesel is going to win hands down if towing or cargo weight come into play. In 2002 my Cummins averaged 18mpg empty and 8mpg fully loaded at 20k, the gas version that farmers still liked at the time was still a 5.9 but labeled magnum V8 got 8 unloaded and couldn't even pull 20k. TORQ, today diesels offer over 800lbs, where does a gasser exist that has 800lbs of torque (besides tractor pulling and drag cars). Longevity is only realized if you keep the truck longer, miss appropriation and early resale hurts management strategies. You see 1999 SD F450 for over $10k in resale all over the net, not auctions. I can't find a gas 1999 F450 for more than $5k. New strategies can also cancel cold weather states cause diesels have overcome that hurdle. Now if you don't need enormous torque and don't know how keep your trucks up to a safe 200k mileage rating then go gas cause your not smart enough to play the diesel game.

  26. 26. Joe Hendrex [ August 26, 2016 @ 06:31AM ]

    I may be wrong but it seems like the data for Your argument for gas engines is based on 10 year fleet rotation , I opperate 15 trucks all Chevy 2500 that pull 10,000 pounds or less I have both diesel and gas units on average my diesels get 33-35% better fuel mileage but the up front cost is about $6000-8000 dollars more per unit.
    We keep our trucks for about 15-20 years depending on usage about 10,000 miles per year on most. With this criteria do you still think gas is the better choice?
    When we switched to diesel the extra up front cost was about 2000-2500 , no smog was required in California , no urea , and diesel fuel was cheeper this is not the case now.
    Does running the trucks out to 15-20 years change your recommendation ?
    And thank you for a very interesting actical.

  27. 27. Ed Wilberg [ August 26, 2016 @ 07:34AM ]

    Well... having read almost all comments I am still scratching my head. I have a 2005 Chevy 2500hd with 6.6 Duramax. It is a beast to say the least. BUT i have also paid to do all the injectors 2x at a cost of 2900.00 the first time. (3200 miles out of warranty) at 220k the cost was 3450.00 Oil changes 2x the cost. I want a new truck but I am seeing tow truck operators switch to gas. My truck tows 25% of the time. My fleet mechanic says to never sell my truck because it was pre-emmissions crap. He also states to now always run fuel conditioner.. more operating cost and God forbid my employees remember to add properly. I could replace the entire engine for what i just paid to do the injectors. I want a new truck bad... just do not want to waste alot of money that is getting harder to come by. I have Hino trucks in our moving business and have not had any issues in 12 years. But a new 33gnw is 125k . Prices are crazy ! Plus just got my new health insurance quote up 27%. Gotta be smart with truck choice.

  28. 28. Dustin [ September 24, 2016 @ 01:25PM ]

    The only people who think diesels are superior is people who like rolling coal.

    My towrig is a 97 F250 HD with the 7.5L (460CID) big block V8. Towing my 30ft travel trailer i get 8 or 9mpg. 13 empty.

    Diesels have higher buy in, higher maintenence, they still arnt all that easy to get started in cold weather, and the only reason you dont see big gassers pumping out diesel numbers is because they have been abandoned. Mainly because the OEs can offer flaccid gas engines and then stick a 5-9k price premium on a diesel model.

    Look at the 3.5 ecoboost in the 150s, making like 400ft lbs of torque. Apply that same tech to something the size of a 460 and that powerchoke wouldnt know what hit it.

  29. 29. Ed-Ro [ September 29, 2016 @ 06:26PM ]

    Dustin, I happen to think diesels are superior. Do you think I like rolling coal? Do you think you know me? Well I'll tell ya, I don't like rolling coal, and I'll go out of my way to insure my diesels don't.

    Applying ecoboost technology (Basically thats a turbo and direct injection…. You know what? Diesels have had that "technology" for decades) There are a number of gas engines that do make diesel-like numbers with one basic exception, they can't match the fuel economy of a diesel when producing diesel-like torque. Basic physics applies. Gasoline contains less energy density than diesel and it's impossible to make gasoline more powerful than it already is. This is the simple key as to why diesel engines make more power on less fuel. You can throw whatever technology you want into a gas engine, but you'll always run against the limits of the fuel itself.


  30. 30. GDW [ October 05, 2016 @ 07:33PM ]

    Well, everyone can argue what they want on brand and whatever you want on pulling power. I my experience though the diesels maybe be needed in cases where heavy trailers are pulled on a day in and day out need. My experience is they are WAY more expensive to purschase and service. My company has had two or more of the big three is trucks. All three have in every case need major repairs ealier and more often than any of our gas powerex rigs. Our gas powered rig run form 8000 to 12000 lb all the time. Our diesel rigs run from 9000 to 14000 typically. Duramax, done will never get another one. The lastest one has spent the last 5 months in the shop more than on the road by a large margin. It is under 100,000 miles. The last powerstroke had two $7000 repairs required in three months at around 180,000 miles. My 5.4L gas motor is at 202,000 and runs a 10,000 lb all the time and often pulls a 4000 lb trailer has had a $900 repair when a coil pack went out and a new start 3000 miles ago, wasn't actually out yet but armature was hanging up sometimes. Our first Dodge is at almost 300,000 but has been throug two turbos and three ac pumps plus at least 6 trips in two months four sensors the would drop the horse power so low you could get to almost get out of a cow way with nothing being towed.
    Plus let's talk about what is good for the air. Yes diesels when left stock have better emissions for air quality but let's talk about the black cloud you beloved diesel engine makes, even worse when they are chipped. Studies by serveral universities show diesel exhaust "clouds" contain not one but several gases that are know carcinogens.
    To sum up, if you need to pull a heavy load, get the right truck.a light commercial truck a kw or freightliner that will go 500,000. They are only about $10,000 more. That is how you save money. And even if you need a class B cdl that is easy to get. No you do not need to go to truck driving school to get a cdl endorsement.

  31. 31. Nathan [ October 19, 2016 @ 11:45AM ]

    This article was written very one sided and the author had an obvious agenda.

  32. 32. Robert Williams [ October 25, 2016 @ 09:32PM ]

    Hey you guys, I'm a rookie to all this so im just reading everybody comments agreeing with all of you lol (even tho I have no clue on what's going on our being said). But if any one can help me, I'm bih to get into the hauling business in like a month, what dually truck and trailer would u guys suggest I get? So many saying bad things and maintenence work consistently I'm scared to get in it now, and I always thought you needed your CDLs to drive the dually,if not GDW please enlighten me with sinn information about that. Please

  33. 33. Tom [ October 27, 2016 @ 11:06PM ]

    I drive a F-350 6.7 Powerstroke Fire Patrol Truck. The other trucks are gasoline, and it really is night and day difference. Going up a grade i can leave it in high gear and still accelerate. With the others i have to down shift twice. We replace our gas engines every six years, and diesels at seven. Many of the other trucks have major transmission or engine problems, so I'm hoping if i can take care of mine and keep the repair costs down, maybe our fleet manager will stick to diesel

  34. 34. Will Jones [ December 19, 2016 @ 03:41AM ]

    First, let me start off by saying I drive a 6.7 ford. While I don't tow everyday, I do put down 50k+ miles a year in very remote sites.

    I agree with this article. The cost of maintenance for my 6.7 is ridiculous, and the cost of parts are not much better. Trying to find a good shop can be challenging, it's rolling the dice at a diesel shop or a backed up or expensive dealer. To do any major work, the whole cab has to come off.

    We can all agree that a diesel wins in the torque category, it's about a wash in fuel economy, and a loss in everything else.

    Gasoline motors have come a long way, 200k isn't pushing it anymore. Where they really win is in cheaper maintenance costs, service costs, and parts. A bad injector pump or turbo is going to run you 10k in a diesel, you can get a whole new motor put in for half that on a gas motor.

    With all that being said, I still can't say that my next truck will be gas. But I can't promise it will be a diesel either.

  35. 35. Richard Coble [ December 27, 2016 @ 04:16AM ]

    Thank you for the article. It made some very good points. I made the mistake of buying a used Ford 08 6.4 diesel. Have had issues ever since. The big three have been made to choke the life out of these new diesels with all of the emissions controls basically making it more expensive to own and maintain. The DPF requirement is in my opinion the killer in most long term issues.
    I have also had many experiences with chevy 6.0s. I work for a large oil field equipment manufacturer which has a ton of these trucks. 2500 HDs. While I love the tourqe the diesel has when pulling, I like even more the less maintenance of the gas engine. My next truck will be a gas for sure!

  36. 36. Don Mitchell [ January 19, 2017 @ 12:16PM ]

    Great article, I have had both gas and diesel trucks over the years starting with the old Ford 6.9, then 350 chevy, 5.8 ford, 7.3 diesel, 6.0 gas, 5.4 gas, 6.6 Duramax, 6.2 Ford,6.7 Ford. and currently running a 2015 Chevy 2500 6.0 gas, I sold my 2011 F250 6.7 mostly because of the potential very expensive problems coming my way, no my 6.0 doesn't have the same pulling power as the diesel but I won't have to take out a loan to fix it either.
    The older Diesels did have some advantages with fuel economy and didn't cost a fortune to repair but not anymore.
    My vote is for gas unless you are pulling heavy loads all the time and really need the torque

  37. 37. Jianhui Hong [ February 04, 2017 @ 08:52AM ]

    There is a recent development that few people noticed. It is called renewable diesel or green diesel. This is not to be confused with biodiesel which contains oxygen has a few shortcomings. The renewable diesel is made out lipids and it is nearly carbon neutral, could be a drop-in replacement for metro diesel. There is no equivalent to renewable diesel in gasoline. If you consider this new development, perhaps you would view diesel more favorably. Thanks, Jianhui Hong

  38. 38. B [ March 01, 2017 @ 01:17AM ]

    problem is everybody is buying the ford and chevy diesel's. There is a reason that the smaller freightliner's even ford's f 650, f 750's come with a Cummins. And no I don't like rolling coal either. I couldn't imagine pulling a trailer with a v10 in a heavy truck getting 5-6 mpg, where is the economy in that

  39. 39. Vince [ July 20, 2017 @ 05:38PM ]

    We have an airport shuttle operation. Ford F-550 with the 6.7 diesel and E-450 with the 6.8 gas. The typical loop is 10 minutes idle, 4 min stop and go under 15mph, 6 minutes 50 mph then 15 minutes idle, followed by 6 minutes freeway, wash rinse spin repeat. These vehicles run typically 20 hours a day. As much as I wanted to like the diesel it's been a maintenance nightmare. Between plugged dpf's and strange surging idle conditions, something is always going awry on the diesels. We have one retired worker who's entire job is to run the diesels at freeway speeds for an hour a week. The gas engines have needed nothing more than oil changes and routine maintenance. Next time around we are going with the gas engines if only to avoid the what seems like constant issues with the diesels. All the vehicles have around 155000 miles on them. Though I know they are never coming back, I long for the days of the 7.3 power stroke.

  40. 40. Todd Roberts [ August 19, 2017 @ 02:44PM ]

    It's embarrassing that this article is just conjecture by the author. The author doesn't provide an analysis of long term, large data sets to back the claims in the article. It isn't until the last few paragraphs that the author provides data and even then admits that some of that data provided isn't really really relevant to this articles topic.

    If you're going to make comparative statements on a subject, such as diesel versus gas engines for fleet vehicles, then put in the required time and effort to collect and analyze large data sets. Instead the author for this article just provides a useless opinion piece.

  41. 41. William Smallwood [ November 01, 2017 @ 04:51PM ]

    NOVAOGAS' SECRET FORMULA to make synthetic Octane gasoline:
    Dear sir, you know that, to make synthetic Octane gasoline from limestone, will both 1) decrease Carbon content of the gasoline from an average of 20 Carbons, to 8 (only 40% as much Carbon!) 2) Liberate 3x Oxygen as 1x Carbon (enough Oxygen to combust the Carbon + 50% extra)! Conventional gasoline, oil, production doesn’t produce any Oxygen! India and The P.R.C. need that Oxygen to breathe! The fresh Oxygen made by switching from a standard gasoline, weighing 20 Carbons heavy, to synthetic Octane gasoline, weighing only 8 Carbons heavy, holds 20x2 = -40 Oxygen heavy vs 8x3 = +24, -16 = + 8 Oxygen comes from the CaCO3 or KCO3, -40 vs (-16 +24) = +8 fresh Oxygen better to consume synthetic Octane gasoline than conventional gasoline! -40 or +8 Oxygen?
    It's mathematically 48 Oxygen better to produce synthetic Octane gasoline than conventional petroleum! That's the math how much fresh Oxygen is made by switching to synthetic Octane gasoline!
    To make gasoline from 8x limestone molecules, just …
    1) Chemically react 8x limestone, 8x(CaCO3), with 8x Hydro-Chloric acid, 8x(H2Cl) making 8x(C)arbon and 3×8 is 24x(O)xygen!
    2) Electrolyse those 8x Methane into 4x Ethane!
    3) Electrolyse those 4x Ethane into 2x Butane!
    4) Electrolyse those 2x Butane into 1x Octane!
    5) Condence that xOctane gas into xOctane gasoline!
    6) I CAN DO IT! You’ll defeat OPEC and get 40% of shares in my patent controling corporation for your funding this experiament while I’ll get 60% of the shares in my patent controlling corporation since it was my idea! Have your receptionist contact William Smallwood @ (0)01-709-834-9700
    You don’t have to worry about my inventive speed, BUT all those people on the Internet wanting to patent how to make oil from rock! You also have to worry about the firms I independently emailed! Financing this experiament is estimated to cost $5,000 – $20,000! You MAY still electrolyse 8x Methane gases into 1x synthetic Octane gasoline EVEN IF converting 8x Limestone or 8x Potash Rock into 1x synthetic Octane gasoline is too expensive!
    What I imagine doing is to first 1) try to chemically convert 8x Methane gas into 1x synthetic Octane gasoline, then secondly 2) try to convert 8x Limestone molecules, 8x(CaCO3), into 1x synthetic Octane gasoline, then thirdly 3) try to convert 8x Potash Rock molecules, 8x(KCO3), into 1x synthetic Octane gasoline!
    That was an offer I emailed to PetroChina but I make the same offer to you if you agree to it before someone else takes this offer! 8 barrels of limestone, 8x(CaCO3), + 8 barrels of Hydro-Chloric acid, 8x(H2Cl), MAKE 1 barrel of Octane gasoline selling for about $67, & 3x8=24 barrels of (liquid only so you can grasp the volume of Oxygen) Oxygen! You make the Hydro-Chloric acid by drilling a salt formation! The Chlorine is electrolysed with the Hydrogen from the saltwater (H20) making (H2Cl) & the Chlorine is electically separated from the salt (NaCl)! The salt is propelled up the drillwell by the gravity of the overbearing rock heading down!
    Octane gasoline is commonly referred to as JET FUEL! But modern automobiles can combust JET FUEL as regular gasoline since the gasoline is today injected into the combustion chamber! The Hydro-Chloric acid is really inexpensive to make after you drilled the expensive well down to the bottom of the salt structure! Then you have all of the inputs to make Hydro-Chloric acid! And the salt (NaCl) is blowing out of the drill hole with the weight of the rock – the weight of the salt!

  42. 42. Marv [ December 25, 2017 @ 06:17PM ]

    After reading everything, my take home is that you are doing constant heavy trailering, where you need the extra torque, that even with the higher gasoline consumption, lower upfront costs and lower maintainence give you lower operating costs OVERALL. I also learned that diesels don’t like idling, just the opposite of what I had believed previously. Thanks, everybody!

  43. 43. Dan Maki [ March 16, 2018 @ 03:33AM ]

    Great article to help me figure out and justify future purchases of gas or diesel trucks under 19,500 GVW

  44. 44. Daniel Girald [ March 20, 2018 @ 09:31PM ]

    The problem is also partially due to oversized Diesel engines being chosen instead of smaller and most often cheaper engines that do get the job done. The turning of Diesel engines into a "luxury" feature is another part of the problem, with most vehicles catering to recreational users instead. A noticeable exception had been the Chevrolet Express with the 2.8L Duramax effectively replacing the 6.6L V8. Sure it sounds quite weird at first, but it seems actually quite justifiable due to a presumably lower purchase cost, and the smaller engine operating more often under high load conditions that provide the opportunity to allow a DPF regen.

  45. 45. Rob s [ April 09, 2018 @ 05:58AM ]

    Your artical is an insight to what's going on in California right now. As a fleet mantainace co. We see our customers dumping the diesel opinion like hot potatoes. The higher costs maintenance and reliability is the deciding factor we constantly have the new diesels broken down waiting for repairs .there nowhere near as reliable as the old ones were and fuel numbers show no advantage anymore for local driving ,OTR is different. As of lately the Ford F550/f650/F750 v10 trucks have been replacing alot of fleet trucks and the owners seem extremely pleased with the purchase they made.On my end it has lowered the bottom line as the trucks are in the shop a lot less for issues not caused by operator error. And power levels for local use is still there.


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