Ok, and what will they do if they find THC or cannabis residue in your ashtray and cannot find weed in the car? I mean, they very well can't bust you for RESIDUE in your ashtray... And to top that off, more newer cars don't even have ashtrays anymore. Tip.... don't use ashtray - use a soda can with soda in it for ashes, and if you are going to put the joint out, use the bottom of your shoe to tap it out - they can't very well bust you for pot residue on the bottom of your shoe - I mean, you could have walked on a roach in the parking lot of the shopping center.