Top Cadillac STS

Cadillac STS

Mileage: 21 mpg combined city/highway
Starting price: $43,135

The 2008 Cadillac STS has a new 3.6-liter, six-cylinder engine that is 47 hp more powerful, at 302 hp, than the same-size engine it replaces. Vincentric estimates that at 2008 standards, the 2007 model gets 19 mpg combined, vs. 21 mpg for the 2008 model. General Motors says direct-injection technology accounts for simultaneous improvements in power, mileage, and emissions. The 2008 model went on sale in June.