While electric vehicles continue to grab the green-car spotlight, an older technology has quietly emerged as a player in the fuel-economy wars: turbocharging.
Once the province of performance cars, turbochargers now power economy cars, family sedans and even full-size trucks. Turbos now account for an estimated 13 per cent of U.S. auto sales, according to Honeywell International Inc., a leading turbo supplier. That's double what it was in 2010.
The increase is driven by ever-stricter federal fuel-economy standards. Turbochargers, which inject compressed air into engine cylinders, enable automakers to squeeze more oomph out of smaller motors.
But not everyone is sold on turbos. Toyota and Honda continue to avoid the technology, and critics, including Consumer Reports, question its efficiency and performance advantages. In a report this month, the product-testing organization found most turbos failed to deliver on advertised fuel economy or to outperform non-turbo rivals with bigger engines.
"There are better ways to save fuel, including hybrids, diesels and other advanced technologies," the magazine said.
Still, automakers including Ford, Volkswagen and BMW are bullish on turbos. Some predict the North American car market will soon look more like Europe's, where more than half the cars are turbocharged.
"We're going 100 per cent into turbo technology," said Rainer Michel, vice-president of product strategy for Volkswagen of America. "From a physics standpoint, nobody will get around it."
Ford shocked the industry two years ago when it introduced a turbocharged six-cylinder version of its hefty F-Series truck, the bestselling vehicle in North America. Noting truck buyers favoured the traditional V-8, Car and Driver magazine said the engine "might as well be a hood-mounted tofu dispenser."
Today, the twin-turbo V-6 now sells better than any other option, including two V-8s, at 42 per cent of all F-150 sales. "It's surprised even us at how well it's done," said Ford spokesman Richard Truett.
But Consumer Reports found the EcoBoost truck achieved 15.7 litres per 100 kilometres in combined city and highway driving, less than its 13.8 L/100 km combined rating from the Environmental Protection Agency and about the same as Ford's 5.0-litre V-8.
Ford released a statement saying the Consumer Reports "findings are not consistent with our internal and external feedback. It shows EcoBoost vehicles lead in customer satisfaction for fuel economy across segments -- including surveys by J.D. Power."
Ford now offers 15 nameplates with EcoBoost engines and plans to add more, including a three-cylinder Ford Fiesta that will be among the smallest engines sold in North America.
General Motors is close behind, increasing turbo models to eight this year from four. U.S. sales of 2013 model-year turbos so far represent 14 per cent of all GM cars, up from seven per cent in the 2012 model year, said Rick Balsley, GM's engineering group manager for charging.
By comparison, gas-electric hybrids account for about three per cent of all U.S. car sales. Figures for U.S. turbo sales include vehicles with diesel engines. Diesels, which also account for about three per cent of the market, have been turbocharged since the late 1970s because of their particular performance and pollution issues. The recent growth in turbocharging involves gasoline engines.
"The U.S. is an emerging market for turbos," said Tony Schultz, vice-president for the Americas at Honeywell Turbo Technologies. "We're growing as fast here as we are in China."
Some major automakers have resisted turbocharging, relying instead on tweaking traditional engines to find power and fuel economy.
"We're not jumping on the bandwagon," Honda spokesman Chris Martin said. "At this point, we have such efficient and powerful engine options that we haven't needed the turbo."
Toyota, the world's largest automaker, is focusing instead on hybrid technologies and efforts to reduce weight and make cars more aerodynamic, specialist Moe Durand said. Today's turbos are impressive, he said, but their efficiency can suffer in real-world use.
"For absolute fuel economy, you're still going to do better with a hybrid," Durand said.
Consumer Reports found turbo engines, across segments and automakers, generally failed to outperform larger non-turbo engines. Ford's 1.6-litre turbo Fusion, for instance, returned 9.4 L/100 km and took nearly 8.9 seconds to get from zero to 96.6 km/h. Honda's non-turbo 2.5-litre Accord, meanwhile, got 7.8 L/100 km and took 8.2 seconds to reach 96.6 km/h.
Comparing turbo and non-turbo versions of the Chevrolet Cruze, the magazine found the more expensive turbo version to accelerate only marginally faster and return identical fuel economy -- 9.0 L/100 km.
"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 the BMW 3 Series it tested recently delivered "both good fuel economy (28 miles per gallon or 8.4 L/100 km) and acceleration." And it said the 2.0-litre turbo four-cylinder in Volkswagen and Audi models returns impressive mileage, though the magazine has not tested it against comparable non-turbo competitors.
-- Los Angeles Times