Limiting car usage would have many benefits for the environment.  Pollution in large cities would be reduced, greenhouse gas emissions would be lower, and noise pollution would be lower.  The simple act of of using alternative transportation would help the environment greatly.

Cities like Bejing, in China, are heavily polluted by emissions from motor vehicles.  This has negative effects on people's health and the environment.  Another point to be made is that if fewer people are driving cars then you won't have to see cars parked all over your city.  But this is America, not Europe; we like our cars here.  I couldn't stand not being able to drive my Ford Mustang GT whenever i feel like it. That is the problem, people will not want to give up driving their cars. I can relate to that.  It is true that driving less will protect our environment, which is very important, but many people will not give up driving.

The real reason why Americans are not buying cars and getting licenses is because of our current recession.  Most people can not afford to have a car, pay insurance, and pay for fuel, especially young people.  No matter what, people are going to keep on driving; Yes, this is off topic, but I don't reallty care for the topic.  So here I'll say: Until the day I die I will keep on driving; driving cars is part of American culture, It will not be relenquished by all.  The answer to protecting the environment needs to be finding a more environment friendly fuel source without turning my Mustang into a Prius.