Just 58 of the 1,199 vehicle models listed in the Environmental Protection Agency's 2008 Fuel Economy Guide (download zip file) get a combined city and highway fuel efficiency of 35 mpg or better.
Industry experts said the first changes will be relatively subtle, relatively cheap and relatively soon. They'll include improved aerodynamics, six-speed automatic automatic transmissions and dual-clutch manual transmissions. Engine-driven components like power steering pumps will give way to electric ones. More efficient gearing and tires with lower rolling resistance will bring still more improvements. The cumulative effect can be significant. Ford says these tactics boosted the fuel efficiency of the V-6 Taurus by 10 percent.
Subcompacts are the fastest-growing segment of the market, but no one expects Detroit to dump SUVs in favor of microcars. Instead, automakers will use a lot more aluminum, magnesium and lightweight steel to reduce the weight of all their cars. Ford has said it will trim 250 to 750 pounds from every car in its lineup between 2012 and 2020.
The most radical changes will come under the hood. Automakers will embrace direct injection -- a more efficient means of getting fuel into the combustion chamber -- in a big way and bring more diesel and hybrid drivetrains to market.
Aaron Bragman, an auto industry analyst with Global Insight, told us. "Two-thirds of the U.S. fleet will have to change to direct injection. One-third of the total market will be diesel, and half of those will be diesel-electric hybrids. Everyone is pursuing a strategy of smaller engines with direct injection and turbochargers."
Chrysler's new Phoenix V-6 engine shuts down three cylinders when less power is needed, improving fuel efficiency by 3 to 6 percent. Ford is developing four- and six-cylinder direct injection turbocharged engines it says burn 10 to 20 percent less gasoline without any loss in performance
The DOE freedom car project is developing more efficient diesel engines and thermoelectric technology which will boost the efficiency of cars and trucks.