I almost tagged you in my response, but wasn't sure if he was driving or not.Yeah that is beyond the pail (sp?) big time.
My brother in law would struggle in that situation. He can pass the drivers test but we do not let him drive. However, he has been in many non driving situations where he gets easily flustered and does not know how to respond. We have taught him to say "I'm autistic can you please help me". We also have a card in his wallet he can give to someone and we have also introduced him to the local PD so that if he does have run ins they know what is going on.