Driving a car with low tire pressure is like driving a car around in the mud all the time. Using the free air compressor at a local auto gas/service station will make your car coast farther, and take less fuel consumption. Assuming that you are keeping up with checking the air pressure in your own vehicle, it'd probably be a good idea to check up on a friend. Come on, how often do you see them adjusting their air pressure? This is a good way to help spread the message of living green.