Life in the fast lane!

We are wondering if this mollusc was fed up with living life at a snail's pace and just fancied trying life in the fast lane! Not really got any idea how or when he attached himself to the back of our car, but that is where we found him when we went to unload the boot at our son's house.

We forgot to see if he was still there later today or whether he had 'lost his grip'. Certainly if he is still on-board he will need to hang on tight tomorrow as we have another journey planned.