Ive hit the back of a car once on the bike, whilst on a club run; we were just about two groups with me at the head of the second chasing back to close the gap on the downhill, when a car decides to overtake but another car was coming head on so they, swerved into the gap and slammed on the brakes. There was a wee dent in their boot but not a mark on me or the bike and tbh I doubted I'd even touched the car but I gave them my details as technically I hadn't provided adequate stopping distance. etc; surprise, surprise they never came back to me however.