What makes you so sure? It takes a lot of political will, and the problem is that some thinks such implementation is too "Communist", "liberal" or "left wing" or simply for that matter, a degree of government regulation and intervention in a such a scale that Americans are unfamiliar with or would not be comfortable with. Although for other countries, such spartan measures would have been typical. Most countries have tighter fuel and safety regulations than in the US, including Japan, S. Korea, much of Europe, and China at least on the fuel part (safety regs need some improvement). See taxation on fuel consumption or car engine displacement size. The ability to develop such technologies is certainly there in the US, but the ability to implement them socially is another thing. This is related to the ability to develop and implement economical car technologies, and guess which countries came out ahead in this one. I'm pretty sure there would be wide opposition on the further "greening" of the US. On the other side there are vital and strategic technologies, such as nuclear energy and coal liquification which the greens and the left wing are going to severely oppose as well. When is the last time you have a brand new nuclear plant in the US? So you get squeezed between both sides of the aisle.