How to raise mpg? Turn off half the engine

For example, the 2008 Accord with an 3.5 liter V6 engine and a five-speed automatic transmission achieves 268 horsepower with fuel economy numbers of 19 mpg in the city and 29 mpg on the highway. That compares with an automatic, 2.4-liter inline four-cylinder engine on EX models that generates 190 horsepower with fuel economy marks of 21 mpg in the city and 31 mpg on the highway.

Czapiewski said the technology was ideal for her because southern Minnesota has its share of snow and icy roads during the winter and she wanted to have the power of a V6 engine. But she’s had to commute to Rochester, Minn., for the past four years as gas prices have risen.

Gary Robinson, Honda’s senior product planner, said the automaker noticed a drop-off in V6 Accord sales when gas prices surpassed $3 a gallon in some parts of the country. He said bringing the system to the V6 Accord will help it balance the performance/fuel economy equation.

“We don’t think it’s the mainstream — it’s 25 percent — but there’s definitely that group of people that wants the power but are increasingly unwilling to accept a disadvantage on fuel economy,” Robinson said during a recent ride-and-drive of the new Accord in suburban Washington, D.C.

Honda officials declined to provide a precise cost estimate of the technology. But industry officials said it is considerably less expensive than hybrids, which typically add about $3,000 to the sticker price.

General Motors first introduced its cylinder deactivation technology on mid-size SUVs such as the Chevrolet TrailBlazer and GMC Envoy in the 2005 model year.

In 2008, the technology will be on 16 vehicles, including the Chevy Tahoe SUV and Silverado pickup, along with passenger cars such as the Buick LaCrosse, Pontiac Grand Prix GXP and G8 and V6 and V8 versions of the Impala. GM says it gives up to a 12 percent boost in fuel-efficiency.

Carl Kilby, 61, of Centerville, Va., traded in his 2005 Grand Prix for a new Impala with the system last week, and was surprised when he didn’t hear any noise as the vehicle shifted into four-cylinder mode. “It was as smooth as silk,” he said, estimating it gives him a 4-to-5 mile per gallon improvement.

Chrysler, meanwhile, has used its system on seven vehicles with 5.7-liter HEMI V8 engines, including SUVs such as the Jeep Grand Cherokee, Jeep Commander, and Dodge Durango, the Dodge Ram pickup and passenger cars such as the Chrysler 300C and Dodge Charger R/T. The systems provide fuel savings of 6 percent to 8 percent, company officials said.

The automaker has outlined plans to bring the technology into the V6 with its “Phoenix” family of engines, which are expected to arrive in the 2010 model year. Chrysler has not yet announced which vehicles will use the engines.

Greg Pannone, Chrysler’s manager of powertrain systems development, said the engines help reduce carbon dioxide emissions in large numbers of vehicles while appealing to consumer interest in fuel economy.

“We can come out with technologies that are boutique — 50,000 units, 10,000 units — they’re not really hitting the masses,” Pannone said. “If we come out with something like this V6, we’re hitting the masses.”

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