Autos: Going the Extra Mileage; With gas prices skyrocketing, even American automakers--the world's biggest guzzlers--are searching for new ways to save.(Cover Story)

Byline: Keith Naughton

Inside Ford Motor Co.'s cavernous wind tunnel, a thin stream of smoke glides gracefully over the new Lincoln Zephyr. But what catches the eye of aerodynamic engineer Wayne Koester is a tiny somersault of smoke just where the back window hits the trunk. "Do you see that?" he says, pointing from behind the control-room window. "That's turbulence." And turbulence is the archenemy of aerodynamics. Koester tried to persuade Lincoln's designers to lower the trunk to improve mileage. But they balked, saying Lincoln's customers demand a big trunk to haul golf clubs. The result: the Zephyr gets 45kpg on the highway--1.6kpg less than its sister car, the Ford Fusion.

These days, though, mileage misers like Koester are gaining traction in Motown. With oil prices high and likely to go higher, Detroit is painfully rediscovering the eat-your-peas merits of fuel economy. General Motors and Ford combined to lose $5 billion in their auto operations in the third quarter as gas prices skyrocketed: concern about mileage has jumped into the top five reasons shoppers reject a car, according to new research from J.D. Power.

So the race is on to reverse a 20-year slide in fuel economy in American cars. In wind tunnels and R&D labs, engineers are chiseling away at cars to make them "slippery." And they're overhauling the century-old internal-combustion engine and transmissions to squeeze out a few more mpg.

The latest trend is to shine a spotlight on the guts of upcoming models, rather than just their curvy exteriors. Ford recently unveiled a new V-6 engine and six-speed transmission that it says will improve fuel economy by 7 percent. GM is touting its own fuel-saving six-speed, and Chrysler just introduced its new Caliber small car with a transmission that continuously, but imperceptibly, modulates gears to boost mpg by 8 percent.

The breakthrough ...