The Detroit News has put together a rundown of all the little tweaks automakers are applying, as quickly as possible, to help current models achieve better fuel economy. Since a wholesale re-engineering of every vehicle is impossible, manufacturers are switching to low-rolling-resistance tires, re-gearing transmissions, moving from belt-driven accessories to electric, and so on. Each change accounts for only a tiny improvement on its own, but added up, the results can make a big difference.For instance, the wrapper on the 2009 Chevrolet Cobalt XFE is little changed over the 2008 Cobalt, but underhood the engineers tweaked the intake and exhaust valve lift duration, swapped the transmission gear ratios for lower operating revs, and put on some low-rolling-resistance tires. The result: one more mile per gallon over last year's model, up to 37 MPG. It may seem like a lot of work for that much payoff, but the competitive marketplace is a cut-throat kind of place, and nobody is standing still in the race for fuel economy. [DetNews]
I'm all in favor of changing things like valve lift duration and transmission shift points for better fuel economy since those things can be easily reversed by a little computer engineering if people actually care about the last couple of percentage points of performance, which most people really don't. Offering low resistance tires and a different/more efficient transmission package seem like fairly easy things to put on the option list as well (unless the manufacturers are worried about fleet standards).
@Parramore64: I think I heard somewhere that knowing how to maximize fuel economy by, eg, properly inflating your tires, is unamerican.
@Ash78: Good idea, I'd much rather hear what mileage I should actually expect in real driving situations. (E.g., you're going to get around 9MPG if you do a lot of city driving and treat each light as a drag opportunity.)