Yeah, I think I can remember twice I've done this, once on a long trip, once on a short one, and both times I just used tissues to clean up. Well, to be more specific, put the tissue over the head just before cumming so it didn't go everywhere. It was alright, but there are too many other things to do while driving-- like driving. Just a little too dangerous for me. Can you imagine if you wrecked? What would you tell the police officer? I'd love to hear that conversation. :-D