having resorted to selling cars during the bad dotbomb days (hated doing it but it put food on the table), I can assure you that many old car salesman lie. Their financial interests lie in direct opposition to yours. And if you think a car salesman makes money, think again. The pay structure usually goes like this:
experienced salesman (2yrs and up) - $30,000 on up
car sales manager - $100,000 on up
dealer manager - $200,000 and up
finance department - somewhere in between the salesman and sales manager (still a lot of money)
The reason a car sales manager is picked to be one is because he has shown the ability make sales, regardless of how he gets it done. He could lie, cheat, steal, rob the customer, and 99% of most dealers won't care, as long as he is bringing in revenue. The dealership makes money on every single piece of the deal. They make money on: the trade-in, the new car, the financing, accessories, new car warranties, manufacturer incentives, sales goals, and more.
I worked for one dealership where 2 guys had been selling cars for over 25 yrs apiece. They didn't even break a sweat greeting customers, didn't have to. They had so many repeat customers from clientele they built up over the years.....they sold over 30 cars a month each. They may have been minimum deals but with sales spiffs and bonuses, they were each pulling down at least $5-6,000/month each.
And if you think car salesman are bad, wait until you get to the people who sell financial products! Some of those guys can make as much as Wall Street financial types if they hustle.
The ONLY company I know have that does not commission its salespeople is USAA. But, then again, they are a special case with a specialized culture from serving a specific clientele.