I might have a bit of a unique perspective here. I work for Easy Racers, an alternative bicycle company. We work on streamlined Human Powered Vehicles, the most efficient vehicles on the planet. The super mileage competition cars aint got nothin on us. These super streamlined vehicles are capable of 100mph with one horsepower. The current world record stands at 81 MPH.
http://www.easyracers.com/videos/BM_2004.wmvOf course these are super impractical but the lessons learned are already making it into the car companies heads.
I recently helped Nissan design an Extreme Gravity Racer.
http://www.gravityseries.comIt won the design contest and top speed!
http://www.easyracers.com/vbb/showthread.php?s=&threadid=2128It was truly mind-bending to hear some of the other manufacturers complete ignorance of basic aerodynamics and physics.
I had quite the philosophical discussion (wee bit drunk) with the Nissan Design America's head design guys as to why they aren't pursuing alternative transportation ideas. Basically it boils down to momentum. The car companies all own and/or are involved with all sorts of industries, from petroleum to steel. Electric or alternative cars seriously threaten the existing paradigm. There is so much more to making cars then simply building them. They swear Toyota and Honda are losing money on every hybrid they sell.
But the good news is, with events like the XGR (extreme gravity racing), where a complete grasp of physics as related to creating efficient vehicles is absolutely necassary, I believe we will see some trickle down of advanced efficent concepts.
The bad news is there is simply no way to make an efficient SUV or Truck. Doesn't matter what you power it with, it still takes the same amount of energy to get from point A to B. Efficient vehicles, by definition, must be light weight and aerodynamic. And there is only one way to get Americans (and the rest of the world) to accept that, when they simply can't afford the gasoline for wasteful vehicles anymore.
I drive a Honda Civic (30+mpg) and a Ninja 250 (70mpg). Gas is still close to $3/gal here in the Bay Area, CA.