This isn't the world's most sophisticated application of technology—in fact, it's decidedly low-tech—but for comparison purposes, the 2009 Chevrolet Cobalt XFE is an example of what's possible at a low price when fuel economy is the driving motivation. AutoWeek test drove the car, which in XFE trim gives you low-rolling-resistance tires, an economy-calibrated engine and a fuel-saving 3.74:1 final-drive ratio, all of which GM claims is good for a nine percent improvement in fuel economy.

In other words, it's the same as the base LS model, except that it costs $600 more for the XFE package. AutoWeek seemed to like the car, averaging 32 mpg in the test. Meanwhile, its EPA rated average is 29 mpg, which is as good as a Honda Civic. Good to see GM providing a solid competitor on the fuel economy front—typically its engines never quite match Honda and Toyota in terms of efficiency—and at a low as-tested price ($16,325) to boot.