How to organize an auction between car dealers

A student tells me about CarBargains:

The service costs a couple of hundred dollars and organizes a sealed-bid auction among local car dealers. In my case, they got 6 dealers to bid, and the prices ranged from $1500 over factory invoice to $100 over invoice. The dealer who had the exact car (options, color, etc.) I wanted actually came in with the worst bid, but when I went to their sales manager with the $100 bid from another dealer, and explained to them I would prefer to buy from him but only if he matched the best offer, he instantly agreed and took care of the deal himself. This cut out the salesman saving the dealership the commission and saved me the time and hassle of dealing with a car salesman. Well worth the $190 the service cost. (at least as far as I was concerned)