Here’s an interesting article on ways that automobiles are being redesigned to achieve startling increases in fuel efficiency:
“A modern car’s engine, idling, driveline, and accessories dissipate seven-eighths of its fuel energy. Only one-eighth reaches the wheels. Of that, half heats the tires and road or heats the air that the car pushes aside. Only the last 6 percent accelerates the car (then heats the brakes when you stop). And since about 95 percent of the mass being accelerated is the car, not the driver, less than 1 percent of the fuel energy ultimately moves the driver—unimpressive, considering it is the fruit of 120 years of engineering effort.
Happily, three-fourths of a car’s propulsive energy need is caused by its weight, and every unit of energy saved at the wheels saves another seven units we don’t need to waste on the way to the wheels. Thus, making cars that are radically lighter weight has huge fuel-saving leverage.”
The article goes on to discuss using specialty steels, plastics and carbon-fiber in smaller automobiles, as well as hybrid technology – and then calculates the fuel savings that would result.
In a nutshell, if this sort of presently available technology were widely adopted, we’d pay for it in fossil fuel savings in about two years.
Of course this is all being driven by the economic pressure caused by the present high-prices for oil. (See – there is a silver lining!)