i was driving at 90mph down the motorway and stroking my finger up and down my passengers leg. As she was making encouraging sighing noises i let my hand go between her legs. When this caused low moans, i unzipped her and slid my hand inside. She soon pulled her pants down so i had a better reach. Prettty soon she was shuddering in orgasm. Pleased it didn't take too long as i was using my left hand of course.