All About Medium-Duty Work Truck Engines

January 2009, Work Truck - Cover Story

by Lauren Fletcher & Sean Lyden

Matching a medium-duty truck engine to a fleet application depends on the size truck needed. Here’s a breakdown of what to consider when spec’ing engines for medium-duty trucks up to a 33,000-lb. gross vehicle weight rating (GVWR).

Class 4 & 5 Options

If the truck you need is a Class 4 or 5 (14,001-lb. – 19,500-lb. GVWR), engine selection is relatively simple. In many cases, only one option is available — diesel. Some manufacturers, such as Ford (F-450, F-550), GM (C-Series, W-Series), and Isuzu (N-Series, H-Series), offer both gasoline and diesel. Either way, you’re not overwhelmed with engine options.

How do you decide between gas and diesel on a Class 4 or 5? While diesel offers better fuel efficiency and engine longevity, gas engines have much lower up-front costs — a difference ranging anywhere from $6,500-$8,000 or more, depending on make and model.

Therefore, the key deciding factor is: How many miles per year will you be putting on that vehicle? Do you anticipate putting a substantial number of miles to recoup the higher investment in a diesel in a reasonable amount of time?

A general rule of thumb is 25,000-30,000 miles. If you project going over that threshold, diesel makes sense. If you’ll be doing less, then gasoline may be more cost-effective.

Run the numbers yourself to confirm what works best for you. Contact your manufacturer’s rep for approximate fuel economy numbers for both gasoline and diesel to plug in your calculations.

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