We only use the car for a once a week shop at Sainsburys, if we're going away somewhere for the weekend where public transport isn't convenient, or when univ is in session -- hubby takes it one night a week for a night class he takes. So, to be honest, I can't tell you if we even fill up the gas tank one time per month -- it's probably less than that on average, and obviously more if we've gone traveling anywhere in the car for a weekend or longer.
Other than that - it's public transportation for us -- to work & back every day, as well as numerous day trips in the area that we might make. We also live on one of our town's high streets, so quick small grocery stops, post office, etc are only steps away.