The Aspen was the first truck-based Sport Utility Vehicle commercialized under the Chrysler brand, although the PT Cruiser was the first truck-based Chrysler brand vehicle as classified under Corporate Average Fuel Economy's (CAFE) regulation.

Since CO emissions are proportional to the amount of fuel used, the national Corporate Average Fuel Economy regulations are the primary way in which automotive CO emissions are regulated in the U.S. However, the EPA is facing a lawsuit seeking to compel it to regulate greenhouse gases as a pollutant.

Some Democrats and environmentalists have urged the administration to raise the Corporate Average Fuel Economy standards.

There have been claims that American automakers are motivated to produce flex-fuel vehicles due to a loophole in the Corporate Average Fuel Economy (CAFE) requirements, which gives the automaker a "fuel economy credit" for every flex-fuel vehicle sold, whether or not the vehicle is actually fueled with E85 in regular use.

The E.P.A.'s Corporate Average Fuel Economy rule, in which every alternative-fuel vehicle sold is calculated to get 120 miles a gallon.

A crucial factor was the advent of CAFE (Corporate Average Fuel Economy) requirements from the U.S. federal government, which severely penalized automakers if their fleet average fuel economy dropped below the minimum.

The bill, on which the committee has now nearly finished work, does not state how the requirement would translate into the miles-a-gallon format of the government's existing measure of required fuel economy, the Corporate Average Fuel Economy standards.

For example, in 1987, when the first RPO Camaro ragtops became available, Pontiac wanted to have Firebird ragtops too, but they were so heavy that they would have raised Pontiac's CAFE (Corporate Average Fuel Economy) number too high.