Researchers are competing to meet a challenge from the U.S. Department of Energy, the Associated Press reports: Improve fuel economy 10 percent by converting the steaming hot air coming from your car's tailpipe into energy that can help power the vehicle. It turns out that both GM and BMW are near the finish line with regard to this project.

What's happening here involves thermoelectrics—the science of using temperature differences to generate electricity. The DOE came up with a generator about 12 years ago; back then, they tested it for 550,000 miles in a diesel truck, the report said. That success was the impetus for this challenge, which is to create some kind of device that can augment a vehicle's alternator and increase fuel economy in the process. The report said that we can expect to see the fruits of this labor in production cars in the next three years. I can't help but think it would be a great companion to start-stop systems.