How much does lighter rims improve gas mileage? I have been trying to search the internet for this question and have not gotten a straight answer. I know lighter rims improve handling, braking, accelerating and all that; however, my biggest question is about gas mileage. Is the increase noticable, above 1mpg, or is it very small. The rims i was looking at are 6 pounds lighter each, so would that be enough to notice a difference?