What Kind of Cars Can Conserve Energy?

Electric vehicles use power stored in a bank of rechargeable batteries to run an electric motor that powers the wheels. Plugging them in to the home electric system recharges them. Electric vehicles save energy, because they use power more efficiently than gasoline vehicles, which only convert 20 percent of the energy in gasoline into power for the wheels (see References 3). Hybrid vehicles each have an electric motor and a gasoline engine. They use less gasoline than regular automobiles, and some do not need to be plugged in (see References 4).

Diesel vehicles generally get better mileage than comparable gasoline vehicles. Unmodified diesel engines can also run on biodiesel, a fuel made from chemically processed fat or vegetable oil (see References 5). With some modification of the fuel system, diesel vehicles can also use straight vegetable oil as fuel (see References 6). Biodiesel and SVO can be made with recycled grease and oil from restaurants, which saves energy and reduces accumulation of an undesirable waste product.

Flex-fuel vehicles run on any combination of gasoline and ethanol --- a type of grain alcohol --- up to 85 percent ethanol. This fuel blend, E85, is available from a special pump at some fuel stations. Like biodiesel and SVO, ethanol is a domestic product made from renewable plant resources, such as corn or sugar cane. E85 is usually less expensive than gasoline but results in lower mileage for FFVs running on the ethanol blend (see Resources 1).