Any of the 8th generation front drive Impalas with the V6 (3.4 or 3.8) are going to be the better than any of the previous generations with the V8's. It largely deepens on your driving style. If your driving like the guy that is always getting passed, your fuel mileage is going to be fantastic. Hard acceleration, especially in the city is when the most gas is wasted. Cruising at the 100km/hr speed limit (about 62 mph) will save you about 20% over 120 km/hr (about 74mph), the speed the cops allow up here in Quebec. Also, big bling wheels (20's, 22's) are going to make it that much worse because the engine has to work that much harder to turn those heavier wheels, as well as having alot of extra stuff in the car like dual 14" subwoofer boxes and amps or those old tires that are in the trunk for example.