"When is the best time to buy a car?"

The best answer depends on how you want to buy a car...

If you're the type that wants to sit around and chit chat with the salesman in order to get him to like you hoping to get a good deal, go in the morning/afternoon. You're less likely to piss him or her off by being talkative and he will give you a good price just because he'll get sick of dealing with you after a few hours.

If you're the type that likes to make things happen fast and not b.s. at all, go at night. I usually suggest this method of shopping for people as you really don't give the salesman much of a chance to give you numbers that you don't like. If he knows you're gone if he says the wrong thing, he won't play games.

If you have no idea how you are going to buy a car because you let the salesman run the show... go at night.

Why?

It's a pretty simple answer really... everyone is tired. Typically, the sales team and managers have been working 10+ hours at this point. Going back and forth with another customer is just not on their "To- Do" list. If you go in about an hour before closing time, you're almost guaranteed a "No Games" approach from the sales team.