Your break-even point depends a lot on how much you drive each year. I drive about 3000 miles a year (primarily to get to mass transit) and my car gets about 25 mpg in local driving, using 120 gallons of gas a year. At around $4 per gallon, that's only $480 a year or $4800 per decade. My car is 12 years old, so I'd expect a car bought this year to be more efficient.
