Now that gas is over $4 a gallon, I've gotten much more serious about fuel economy. I have unloaded any unnecessary weight from my car, check my tire pressure religiously, plan my trips and routes carefully, and do whatever else I can think of to conserve gas and use my car as efficiently as possible.
Since I'm doing a little bit of freeway driving with my new job, I've made a committment to drive the speed limit. It's a proven fact that you lose fuel efficiency when you start going faster than 55 mph or so. This is why the federal government lowered the speed limit back in the 1970s.
I have learned that the rest of Phoenix does not care about my fuel efficiency or mpg. They want me to go 80 in the slow lane, by golly! I'm now analyzing the cost/benefit ratio of driving 55-60 mph on the local highways. I can probably eke an extra hundred miles out of each tank of gas by driving 55...but I may get run off the road or shot in the process!