Raising the CAFE standards is the first thing mentioned by any politician when discussing the oil crisis, and they throw out ambitious (to say the least) numbers- 40, 50, even 100 MPG requirements. I guarantee you one thing: any politician calling for 100 MPG CAFE standards either doesn't understand the problem, or is a lying demagogue. Even 50- as a fleet standard, not for a single model- is a fantasy without a breakthrough in basic technology. It might be possible to reach 35- but that's not enough to solve the problem.
Why do I say this? Three sentences: Force equals Mass times Accelleration. Work equals Force over Distance. Power equals Work over Time. What does that mean? That you can only have two- at best- of the three characteristics- size, performance, economy. A certain level of performance is absolutely required for safety's sake- that's part of why they don't allow bicycles on highways- and a certain size is needed for survivability. Those requirements put limits on the third factor, economy. The smallest car in mass production (it doesn't even pretend to have a back seat) that will accellerate quickly enough to merge on a highway ramp (just barely) or drive in the mountains (possibly), and meet American safety standards is the Smart Car, and it only gets 40 city/45 highway. Hybrid cars, despite some claims, don't do any better in real life. Nothing with an internal combustion engine is ever going to do significantly better, (many people don't realize this, but despite the great strides we've made in reliability and cleanliness, the specific fuel consumption of the internal combustion engine has improved very little in the last 75 years) and there is no technology yet ready to replace it. (See Who killed the electric car? ) These are not Republican or Democratic positions, these are physical realities.
Richard Nixon, for all his other flaws, understood this; that's why he lowered the speed limits instead thirty years ago during the first oil crisis- doesn't anyone remember the double nickel? That is still the only quick answer, if it weren't for the fact that the American public is firmly in Sammy Hagar's camp. Finding an alternative fuel will take longer and be more expensive, specially if you want to reduce the carbon footprint at the same time- hydrogen is the only candidate we have at the moment fitting that description, and we're years away from making that practical. Light rail is not an answer- a rail system extensive enough to seriously cut into our gas consumption would take decades to build, and be so hideously expensive as to be "the moral equivalent of war".
It's time to realize that "I can't drive 55" is just 80s big hair rock, not a lifestyle.