I was on a 3 day film shoot this past week and we had several LEO's onsite for security and traffic control. Since I was on lockup duty (keeping non-crew out of the area), I was hanging out with them quite a bit. Many of them already knew what ecigs were and I gave some ECF cards to a couple who asked for more information.
Hopefully word will get around the departments and these types of incidents won't happen very often.
Personally, I vape in my car quite often and I've never had an issue with being pulled over for it.