FE on my olds is starting to dip, but not why you might think. in central FL, there are very few really cold days to affect it. however, this time of year i drop off/pick up the kids to/from school one day a week to give wifey a break. not complaining tho. last year my mpg dipped to 20 from 21-22 w/out acetone. this year, same situation w/acetone dipped to 24.4 from 25.5(first fill-up). no question that the acetone helps my car, but also no question it does NOT help my wife's camaro. can't say why except that her miles are not nearly exact like mine. also she won't let me test her car for a 2-3 months. wonder why?