There are lots of ways, depending on the dealership. Others watch videos and read books. Many dealerships have weekly sales meetings in which they conduct role-playing sessions. Remember, car salesmen get to practice their game every day, all day long. That's why they're so very good at it.
Car salesmen have a reputation as being dishonest.
That's not, however, because lying is a part of the game. Rather, it's because lying is a result of the pressures of the game. Remember, car salesmen work entirely on commission. If they don't sell a car, they don't eat or pay their rent. Yes, of course, just as there are honest politicians.