I bought a car that got better fuel economy.

The car payment hurts, but I fill up less often. Also got a better paying job that was closer to home. Altogether I'm on the + side.
But really... I still drive like I like to drive. I go fast on the highway, but in the city I don't floor it off the line and I coast when I see a light. If I saw a huge difference I would modify my habits, but the damn car is just so good on gas no matter how I drive. It's not worth the extra 2mpg to slow down that much.

In the Alero it did make a lot of difference to set the cruise closer to 70 and watch how much pedal you give it off the line. A lot of that is the difference between an auto an manual, too.