Whenever I am at a competition or on a training course, my dogs will be in the car most of the time they are not working. It is of course all caged out so each dog has their own area, and the doors of the vehicle can be left open on a hot day. You are never far away from where the vehicles are parked, although I accept there is a small chance of dog-napping, I can only ever once remember a vehicle being taken, that was from a competitive obedience show a few years ago.