EPA's Hybrid Payback Calculator

The EPA has posted a very nice interactive hybrid vehicle payback calculator.  It lets you quickly adjust assumptions to see how long a hybrid or electric vehicle would pay for itself based on fuel savings.

For example, comparing a Chevrolet Malibu Eco to a base gasoline Malibu, 12,000mi/year, 60% city driving, gasoline at $3.75, the tool says that you would save a whopping $200/year on gasoline, and that the $550 MSRP difference would be paid off in 2.7 years.

Clearly, the Malibu Eco isn't an irresistibly good deal, because that $200/year in fuel savings is going to cost you several cubic feet of trunk space.