Researchers work to turn car's exhaust into power

a ten-year-old prototype of General Motors thermoelectric generator

Researchers are competing to meet a challenge from the U.S. Department of Energy: Improve fuel economy 10 percent by converting wasted exhaust heat into energy that can help power the vehicle.

General Motors Corp. is close to reaching the goal, as is a BMW AG supplier working with Ohio State University. Their research into thermoelectrics — the science of using temperature differences to create electricity — couldn't come at a better time as high gas prices accelerate efforts to make vehicles as efficient as possible.

GM researcher Jihui Yang said a metal-plated device that surrounds an exhaust pipe could increase fuel economy in a Chevrolet Suburban by about 5 percent, a 1-mile-per-gallon improvement that would be even greater in a smaller vehicle.

Reaching the goal of a 10 percent improvement would save more than 100 million gallons of fuel per year in GM vehicles in the U.S. alone. - yahoo

In general I think our technology is still very primitive. Advanced technology will be safe, clean and largely undetectable.