It's always important to research the car you want before you make your first contact with a sales rep, but being knowledgeable about the vehicle's specs can also help you gauge his or her integrity.
"Sometimes, I will put a fact out there and make it wrong," Banez says. "For example, I tell them I would like to get the base model with leather, when I know that isn't an option. If they say, 'Yes, we can get that for you,' then you'll know they're making promises they can't keep."
There is one caveat on this tip. Montoya says when testing the car seller's knowledge, be sure to ask a question with a fairly obvious answer. Even good sales reps may not be well-versed in obscure facts like gear ratios and exact wheelbase length. "Not every salesman is going to memorize all the stuff in every car they sell," he says.