I have worked for new car dealers in the past, and what a sham a lot of it is.
Here are some things that I remember:
Don't get pinstripes, custom wheels, custom stereos or anything else that didn't come on the car originally. That's where the dealer makes their profit. Pinstripes applied by a professional? $6 per car. Your cost for pinstripping? $100+. The salesmen rely on that sort of thing to make some coin for themselves.
We had a new owner once who would hire 30 new car salespeople every month. He'd have a one-day training class, and he would lose a few that day. The rest would work their butts off for zero commission the first month. All new car sales commissions went to him, not the salesperson. He'd lose most of the salespeople after the first week because he would work them over 80/week. The second week, he'd lose most of the rest, and by the last week of the month maybe one person would still be there. Time for a new training class promissing "lots of potential if you're willing to work hard".
One guy I made friends with came to say good-by after two weeks. He had gone home and his wife packed her bags and the kids and told him, "it's either us or your job...which is more important?" He chose the more important, of course. I finally got tired of the owners and their crap so I left. A friend of mine told me that he was hired to be their new parts manager, and I told him he wouldn't like it there and told him some stories. He was excited and the very first day he went to work to be the manager he was greeted by the feds at the front of the lot, and told that the dealership was closed and under investigation. Lots of stuff going on there. I heard one story that there were a lot of new cars being stolen. When some of them were found they actually had the same ignition cylinder and key that came with the car new. Turned out that sales were slow so someone made extra keys and cars were being driven off the lot so they could collect the insurance money.