What's the deal with the invoice price of a new car?

The price of the average new car sold in the U.S. right now is $30,700, according to TrueCar.com.

Whenever people talk about buying a car, the invoice price always comes up. How do you use that information when negotiating the deal?

Jack Gillis, an auto expert and author of The Car Book 2014, tells me there are two things to remember about the invoice price.

"It isn't necessarily what the dealer is actually paying for the car because there are all kinds of separate background deals between the dealership and the manufacturer. However, it's a very good barometer," he said. "So if you can get a car around invoice price or maybe a hundred or $200 over invoice price, consider that you've got a great deal."

Just make sure you don't get sold add-ons that you don't want and don't need  - such as fabric treatment, undercoating or extended service contract - that will drive up that price, Gillis said.

Listen to Gills talking about buying a new car on KOMO's ConsumerMan Radio Show with Herb Weisbaum.