Different gas prices for different size engines.

If the U.S. government would make law to charge differently for gas by the size of the engine, it would encourage people to buy cars with smaller engines to pay less for gas and in turn help the environment. Exceptions could be made, for example, a family with five or more members would, of course, need a bigger car. They could be exempt from paying more for gas because they don't fit in a car with a smaller engine.