I have a fun little project for my first post:
My daily driver of choice isn't quite as economical as some of the cars I see here, but it's hardly a gas guzzler. I drive a 1994 Mazda Protege LX with the DOHC 1.8L 125hp engine. Unlike it's SOHC counterpart, the gearbox has much shorter gear ratios that make driving a frustratingly high-rpm experience at normal highway speeds. After some research, I discovered that a taller gear was available from a Ford Probe (this platform shares many parts with several other cars).
Some pictures:
Check out the full article I wrote about doing the mod.
I've seen a 10% improvement in highway mileage (which varies significantly with my driving style on a given tank). Since the change in gear ratio is also about 10%, this seems pretty reasonable to me.
-Chris