"The small-displacement turbos certainly are not the magic bullet in terms of fuel efficiency," said Jake Fisher, director of automotive testing at Consumer Reports. "Their EPA ratings look good on paper, but in our testing, they not only don't perform as marketed, but not as well as conventional powertrains."

GM responded with a statement: "If you have a heavy foot on a turbocharged engine, you're not necessarily going to see a lot of fuel economy benefits. As is generally the case, the improved fuel economy you get is really dependent on how you drive."

Consumer Reports did not pan every turbo model, noting that the BMW 3 Series it tested recently delivered "both good fuel economy (28 mpg) and acceleration." And it said the 2.0-liter turbo four-cylinder found in Volkswagen and Audi models returns impressive mileage, though the magazine has not tested it against comparable non-turbo competitors.

The cult of turbo

Today's turbo renaissance marks a turnaround from the bad-old days of turbocharging in the 1980s. Back then, the technology became the automotive equivalent of crack cocaine — an intense high followed by self-destruction.

Images of exotic turbocharged sports cars graced the walls of teenagers' bedrooms everywhere, and the word "turbo" embedded itself in the culture as a synonym for fast and cool. It has since been applied willy-nilly to unrelated products such as sunglasses, razors, even tax software.

The reality of owning the turbo cars proved less cool. Turbochargers often blew out before 100,000 miles and damaged engines. Consumers started to see them as disposable vehicles. Resale values fell through the floor.

Driving turbo cars proved an acquired taste because of "turbo lag" — the power didn't kick in until the middle of the rev range, creating a herky-jerky driving dynamic.

"In those old turbo cars, you'd rev up the engine and all of a sudden — bang! — you get the turbo power. For daily drive ability, they were very bad," said Michel of Volkswagen. "On a 180-degree highway ramp, hit the gas at the wrong moment, and you're off the road."

Today's new slate of turbos drive better and appear, at least initially, to have overcome the reliability issues. That's because the technology has been honed — tamed, really — with a combination of other complementary technologies, including engine-management systems that can precisely calibrate air, fuel and spark.

Today's turbocharged cars target an entirely different consumer, GM's Balsley said. "Now we're putting turbos in cars for consumers that may not even know they have a turbo — or care."


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