scirel, I am more inclined to follow your friend's practice. I wouldn't think the ticket being in the car would make a lot of difference. If not there, wouldn't the thief just claim to have lost the ticket? Also, if the facility is capturing license plates of parked cars, it would seem to be at least as likely that they could trace the departure time by the plate, rather than the ticket (unless they were associating the ticket number and license plate when you entered the garage).