Don,

If you do some calculations, it might actually cost you less to trade one of your current vehicles for a vehicle with better gas mileage. It all depends on how much you drive. I did the calculation and my wife and I are borderline. However, when we move in a year or two to be closer to her work and my parents, then it will not make any sense for us unless gas is $10+ a gallon. Now, if one of the cars needs to be replaced, you can bet it will be replaced with something that gets much better gas mileage.