[Thymeclock]

I was driving my wife's 2009 Aveo the other day, and I realized something was different between this new car and the 20 year old others that we have. I try to coast as much as possible (even with the automatic in 'drive') and I occurred to me that when I take my foot off the gas on the new car it doesn't glide as well as my other old beaters do. I'd attribute this to the wheel bearings (and other components) being new and tighter by comparison. (It might also be the nature of the transmission, but my perception is that it just seems to not roll quite as easily.)

I've heard it said (in the case of the Aveo) that the gas mileage will improve as the car gets older. (We're currently getting a disappointing 22.5 MPG in all city driving, and that's with using the scan gauge and driving conservatively.) I find it hard to believe that mileage or anything else will get any better as a car ages, but in thinking about it, it seems possible that worn and looser parts might exhibit less rolling resistance. Also this might explain another factor as to why cold weather operation reduces FE: the colder the temperature, the less viscous grease and lubricant becomes, and the resistance is increased.

If I'm correct, you might want to add this to the list of suggested modifications. Not that we should want want sloppy steering or suspension, but if wheel bearings or brake components are adjusted too tight or there is any increased resistance in the rolling ability of the wheels, it's not going to help FE any.