It happened. In our lifetimes. Under a Republican President.
Sure, it's a small token: existing technology solutions phased in over ... do I hear one year, two years, five years, ten years? No, a generation!
What do you estimate the odds are that the US, which is near the bottom of most industrialized nations, at around 25 mpg, makes it up to where Japan is, at 45+ now (and rising)? The legislation sets the bar in the mid-thirties. Even China is higher than USA - how do you think that plays when we sit at the table to talk about paying the cost for global warming (you know, as in "show American leadership")?
Here is another interesting set of statistics. Over the past three years, Exxon has returned $56 billion in cash, via stock buybacks. That would have funded the entire capital expense for both GM and F for the three years, and get this - with eight and half billion dollars left over! In other words, if we didn't have "free" markets, one might have re-directed the oil profit 'excess' to kick starting the huge-cost development cycle of the major auto dealers to the tune of three consecutive years!
Of course, to Cheney-Bush, it is more important that we fight al-qaeda "over there" ...