I can't afford a new car now, so my contribution is to "bundle" my errands. Every night I make a list of what I need to do the next day. If I MUST drive somewhere, I make a mental map of the area and actually rewrite my "must drive" list in the order which takes the least number of miles. Some days I can save up to 10 miles by thinking ahead and not retracing my "steps". That's a real savings over a month and helps me feel better about having to drive at all. I'd love to hear other ideas - there must be other ways to get those pesky errands done and contribute to our green cause.
I don't know if it works the same on a traditional engine, but I know if I accelerate slower on my hybrid I get a better gas mileage because it can get enough power from the battery for a longer period of time. And stating the obvious - coasting as much as possible would help (like if you see you're coming to a stoplight/sign there's no reason to hurry up and get there then have to break fairly hard. Try cruising a little more :-> Ah, and I seem to recall "properly inflated tires" as a no cost fix to help out. Something like 1-2 mpg improvement rings a bell.
