My Mother used to work for Toyota and Honda here in the bay area. She sold Joe Montana and Jerry Rice their 4runners. She taught all the little tips and tricks for negotiating. I still have her around when I go to buy a car as she likes to jump in and do all the talking. I just let her go nuts and I normally end up with a great deal or moving on to the next dealer where I will get a great deal.
EDIT: She was a manager/accountant and spent most time in the office, not out on the lot like a vulture.