Using less fuel is one way you can make a difference. A no-cost way to immediately save on your fuel usage and expense is to drive gently.
A light foot saves not only gas, but your temper, your brakes, and wear & tear on your vehicle.
Remind yourself, and others on the road, by applying the Drive Gently bumper sticker. It is available, at cost, at www.cafepress.com/drivegently.