SAN FRANCISCO - The number of cars and trucks used by San Francisco workers could decrease by at least 20 percent within years under a plan from Mayor Gavin Newsom, who is looking to further cut costs and reduce carbon emissions, according to the San Francisco Examiner.

Newsom has taken a number of incremental steps over the years to transform the fleet into a greener operation with increased oversight of vehicle usage. Newsom's latest effort would require departments to reduce the number of passenger cars and trucks used by their employees by 20 percent — 5 percent annually — by 2014, according to legislation introduced to the Board of Supervisors.

The fleet reduction effort will also come with strict reporting and oversight. Each year, department heads would have to submit to the Board of Supervisors budget analyst a report detailing how they are complying with the mandate.

If a department head wishes to buy a new passenger car or truck, the purchase request will have to be accompanied by a written explanation.

The legislation also requires the removal by 2014 of all vehicles that are 12 or more years old, which could be counted toward the 5 percent reduction requirement.

The City's fleet has a total inventory of 6,881 vehicles and equipment, which include 1,591 passenger cars. The City's fleet, not including emergency response vehicles and equipment, has been reduced by nearly 17 percent in the last five years, the Mayor's Office said in July.

In recent months, Newsom announced a partnership with City CarShare as an alternative to having to purchase new vehicles and be able to reduce San Francisco's fleet size. Additionally, the City is rolling out new software from GPS Insight that will track vehicles' mileage, gas, and time running.

The legislation requires approval by the Board of Supervisors to go into effect, reported the San Francisco Examiner.