um, to avoid getting caught, dont smoke publically in your car. i know, that was stupid, but its true. i used to smoke in my car when i was in highschool, but it always kinda ruined the buzz cuz i was paranoid about getting caught. try to find a place outside to smoke, it's a lot better when you don't have to worry about getting busted the whole time.
plus, driving stoned is a bad idea. it doesn't impair you as bad as other drugs such as alcohol, but it still does impair you to a certain degree. plus, if you get in an accident, your fault or not, you will be busted big time if you have THC in your system.