auto
Gas-saving devices mostly a scam

The real scoop

Still, innovative breakthroughs happen every day in every field. Who says the gadget on the Internet isn't that phenomenon?

"These vendors will probably tell you there is some sort of conspiracy among the automotive manufacturers, but nothing could be further from the truth," Cox says. "They (manufacturers) do huge amounts of testing and put a lot of resources into research. It's not something they take lightly."

Consider the 1981 air-bleed device that the EPA discovered really did affect fuel economy positively. It shut the air-conditioner off during short periods of acceleration because the engine was already working hard. Today, new cars don't need the product, because Ford, General Motors and the gang incorporated that winning technology into their designs.

But the chances of lightning striking twice like that, particularly with piston engines, don't impress Duleep.

"It's a very small chance, largely because the piston engine has been around for more than 100 years. During this time, every particular angle has been explored, and the chance of somebody overlooking something fairly obvious is pretty small," he says.

For the auto-mechanically minded, it's common knowledge that inefficiencies in the engine and transmission account for much of a car's energy loss, and those are the areas where Duleep searches for improved fuel economy.

He likes GM's Active Fuel Management engine that uses eight cylinders when you need peak power on an interstate entrance ramp, for example, but cuts down to four cylinders during normal driving conditions. (DaimlerChrysler calls its version the Multiple Displacement System.)

"Those are the kinds of things that help you reduce the 20 percent to 37 percent gap between maximum efficiency and the typical efficiency in a car's energy use," Duleep says.

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Cox, too, points to gas-guzzling problems in his booklet: If carbon buildup or running a few degrees too warm causes the engine to knock, the powertrain control module is programmed to retard the ignition timing to correct the problem. However, this retarded timing reduces the engine's power and, thus, burns more fuel. Conditions like combustion chambers that are too hot, worn piston rings, valves and gaskets or inadequate electrical power from the battery can also suck up to 8 miles per gallon off your bottom line.

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