Is it worse to start and stop your car, or let it idle? I just got my first new car in many years and I got all obsessed with mileage, although not to the point of hypermiling, like to the point where I'd shut it off in a restaurant drive-up or while sitting in a car wash. My question is, which is worse? Should I let it idle for five minutes or stop and start it twice in five minutes? I've learned on this board that idling can cause fuel dilution but also that frequent starts and stops cause engine wear. I suppose if I let it idle a few minutes I'm going to drive the rest of the way home and burn off any diluted fuel? Did I just answer my own question?