The next thing in greener cars doesn't need hydrogen, lithium-ion batteries or even a power cord. In fact, it's based on century-old technology that has been used on trucks since before World War II: the turbo.

The next thing in greener cars doesn't need hydrogen, lithium-ion batteries or even a power cord. In fact, it's based on century-old technology that has been used on trucks since before World War II: the turbo.

Under pressure to reduce emissions and increase fuel efficiency, automakers quietly are turning to turbocharging as a relatively inexpensive, easy-to-implement technology that soon could be a permanent staple on internal combustion engines.

That's because turbos, high-velocity fans that recirculate and compress exhaust gases back into the motor's cylinders, can increase fuel efficiency by as much as 30 percent, while at the same time increasing power output. Thanks to that increased power, smaller engines can be used, reducing weight and further increasing efficiency. And because it's a proven technology, the R&D costs are enticingly low.

"There isn't a dynamometer in Detroit that doesn't have a turbocharged engine being tested on it right now," says Eric Noble, president of Carlab, an automotive consultant in Orange, Calif. "There's still a lot of fuel savings that can be gotten out of a traditional engine."

Automakers are cagey about announcing how many cars will get the turbo boost, but General Motors executives say they are considering putting turbos on even their largest passenger vehicles, while Hyundai just announced its first turbocharged car, the Genesis coupe, for the U.S. market in a dozen years.

Volkswagen and Mercedes are preparing to hit the American market with new turbocharged diesels starting next year. And last week at the Los Angeles Auto Show, Ford chief executive Alan Mulally announced a major initiative to begin putting turbochargers and a related technology, direct fuel injection, on a large portion of its fleet in the near future, calling the move a "cornerstone of Ford's near-term plan."

The first Ford vehicle to get the boost will be the new Lincoln MKS, which will be introduced this spring with a standard engine, but will go turbo by early 2009. The new engine will be smaller — 3.5 liters versus 3.7 liters — yet have better performance.

"This is not something on the drawing board. Turbos are here," says Adriane Brown, president and chief executive of Honeywell Transportation Systems, the leading turbo manufacturer, with $2.5 billion in turbo sales last year. As turbos gain more acceptance, she expects sales to grow three times faster than the automotive segment in the next few years, or about 8 percent.

Some carmakers are just now embracing the technology (and a very few still shun it), but others have been pressing the turbo button for years. GM's Saab, for example, has long used turbocharged engines, and Subaru has had them in cars for 25 years, including four current models. In Europe, turbocharger-equipped diesel engines are far and away the most common engine type, approaching 50 percent market penetration. Yet in the U.S., said Honeywell's Brown, only 6 percent of cars and truck are "boosted."

That gap, experts say, largely is due to American tastes — and prejudices. Simply put, Americans want big, heavy motors, and they associate displacement (the volume of air and gas drawn in by an engine) with power. Turbos are seen as accouterments for tin-can sports cars and low-slung street rodders, hardly something useful for towing, say, or even lugging kids to soccer practice.

The reality, however, is that turbochargers have been on heavy-duty trucks in the U.S. for years; the Big Three automakers had 19 different turbocharged diesel trucks in their 2007 lineups, according to Edmunds.

"The U.S. is probably the last market to look at the upsides of downsized turbo engines," said Mary Brevard, spokeswoman for supplier Borg Warner, which saw sales of its turbos increase 17 percent last year, to $825 million. "Americans think bigger is better, but if they drive a turbo, they find out it's a (powerful, high-performing) car."

They might be finding out whether they like it or not. With government fuel consumption standards expected to rise significantly in the near future, many automakers see turbos as the least expensive and easiest short-term way to increase efficiency. In July, a few months before revealing its experimental, 68 mpg hydrogen fuel cell car at the L.A. Auto show, Honda unveiled a clean diesel with a turbocharger that gets 63 mpg. Unlike the clean diesel, which could be on the market in no time, hydrogen cars cost as much as $1 million each and are at least a decade away, most experts say.

That kind of thinking is sinking in, even with the most conservative of carmakers; that's why analysts expect turbo penetration of the U.S. market to reach 15 percent by 2012. "We're looking at equipping very, very large cars with very small four-cylinder, turbocharged engines," said Bob Lutz, GM vice chairman, mentioning the Cadillac DTS and the soon-to-be available Pontiac G8, both of which have eight-cylinder motors.

The notion that a high-efficiency, carefully tuned four cylinder seamlessly could replace the big-block monsters that have defined American roading for decades, is practically blasphemy in some circles. Yet for Jake Fisher, an engineer at Consumer Reports, it's an unavoidable step. He describes being amazed driving a turbocharged BMW 535i, and even more so when he learned it got three miles per gallon more than the nonturbo Infiniti M35.

"It has 300 horsepower and still gets 22 miles per gallon," he says. "That's what a turbo does."