Interested in an energy-efficient auto? You're in luck. That's because nearly every major car company has a hybrid line, or has plans to introduce one soon.

But enter the showroom, and instead of seeing green, you may be seeing red. Many of the market's hybrids—cars which combine gasoline engines with battery-powered electric motors—forsake fuel-efficiency in the name of power and performance.

Mild-hybrids may not save you money at the pump, but they are a little nicer on the environment.