Well, admittedly, fuel consumption by (all) cars is a serious problem. If the whole world, at current population, tried out the lifestyle we damn-lucky Americans were born into, it would take at least 5 Earths to support it (I believe.. was brought up in a class last year). There's a lot more at play here than "I don't want to give up my car". If you look at a map of a U.S. city, most aren't built in a manner that can accommodate any other transportation: people live twenty-or-more miles away from their workplace, and few want to manage an hour-and-a-half bike ride (maybe an hour if you're fast) for a commute. Many don't have adequate bus systems, let alone trains, and even if they do the buses often have a bad reputation (sometimes deserved). There's an interesting blend of social stigma operating, too: people will frown if you drive a Hummer, but they'll give you funny looks for coming in sweaty.
Not to mention that we have a pretty strong oligarchy/plutocracy. The rich rule this place, more or less. I think "the people" have some power, but alone, the 40% of us who are concerned to some degree or another, won't manage to pass legislation actively limiting emissions to a reasonable standard. There's also the classism that goes on: being "green" is something upper-middle-class people can afford
None of this is an excuse, per se. Something does need to be done. I actually was recently talking about a project that would be so f**king cool
(and rather prohibitively expensive). Imagine that even a few of the highways in the U.S. were built out of solar panels, covered by glass built to be driven on (which actually exists, according to the engineering major who was telling me about this). They're in the sun all day, and have massive
surface area. Not to mention, if we built pull-outs with battery boxes, the electric car would be so much more feasible. So when you buy your car, you buy a battery plus a certain fee for re-charges; you get to one of these pull-outs, slide your credit card (also insurance against thefts, as it would charge you if you didn't return it), put in your old one, pull out a fresh one, and off you go.
SO f**kING COOL.
And so off topic.