Today (or yesterday depening on where you are) i bumped my friends car while following her. A guy 2 cars ahead stopped suddenly and i could not quite stop in time (i was not going very fast but he stopped with absolutely no warning). We pulled over and checked the cars and on the one i was driving there was a small dent (which can be popped out by another friends uncle today) and her car was 'fine'. When ariving at our destination and double cecking we noticed that the back of her car was slightly impresses so that where normally the wheel would have a bit of space all around, at the bottom it was pushed in (i was driving a suziki jimny and she was driving a rav 4, so mine is a bit lower). We are both relitively new drivers and these are our parents cars. Her parents are away and don't come back until tommorrow but before we saw the squished space we decided we would not tell our mums and her dad. If her parents notice then i have told her i will find the money to fix it (i plan on getting a job anyway and it probably just needs 'popping' out again. What should i do? Tell my mother now or wait to see if there is any point worring? I am up at 1 in the morning now because i don't know what to do. TIA.