With the $$$$$$ of fuel going through the roof - and I know bigger means more fuel - aren't these a real expensive option? Now I know when some jeak next to you wants to have fun bigger is always better - BUT with fuel heading towards $4. 00/gallon - and don't laugh - these ***** will have it there this summer - if you're driving at say 65 - what difference in Fuel Mileage can you expect say between a 2. 4 and a 4???????