I used this process to buy my last car. The difference between the lowest two bids was several thousand dollars, and both were far less than I got from casual browsing in dealerships. I had a drive 30 miles to get the car I wanted, and the experience was the best I've ever had, though it will likely be my last. I don't think I'll ever buy a new car again. There are too many deals to be had for slightly used cars.