I still do not fully understand why vehicles in Europe can obtain 50mpg whilst the average US vehicle struggles to get 20mpg. Why does the auto industry consistently fight any moves to increase the fuel efficiency of vehicles in the US? Why is the US at the bottom of the list when it comes to fuel efficiency? Why have most other countries mandated increases in fuel efficiency whilst the US tries to remain level?
Car companies build and sell the cars that people want to buy. European governments, to my knowledge, have NOT mandated fuel efficiency levels, but rather have enacted policies which cause the cost of fuel to be very high. High fuel costs drive the consumers to smaller, fuel-efficient cars. In the US, with relatively low fuel costs, consumers flock to big, high-performance vehicles.
One of the easiest ways to increase fuel economy is simply to SLOW down. When I drive across the state to pick up my son at college, I drive about 65mph, and often will not pass a single vehicle, but am passed by countless vehicles at high rates of speed.
As was noted in previous posts, despite high gas prices, Americans are driving more, and demand for fuel is UP. Ask any car dealer, who has on his lot two identical cars, one with a 4-cylinder engine, one with a 6-cylinder engine, which will sell fastest? Horsepower is what consumers want, far more then fuel efficiency.
The government mandates for higher fuel efficiency is simply the government taking the easy way out; pushing the problem on someone else, a "big bad corporation". The government could lower the speed limit to 55mph, or raise gas taxes to European-levels, but that would be very unpopular politically.
Trying to reduce US oil dependency by forcing automakers to produce fuel efficient cars is like trying to reduce American obesity by forcing clothing manufactures to make only small sizes.