The mountain bike industry has been transitioning to direct to consumer for the past couple of years and there has been some serious growing pains. The one model that seems to work best - or piss the fewest people off - is a hybrid where the consumer can buy directly from the manufacturer or a dealer. If purchased from the manufacter, the bike is shipped to the consumer's local dealer and the dealer gets a portion of the sale. If the manufacturer doesn't have a dealer nearby, the bike is shipped directly to the consumer. I can see this model working for the auto industry as well. Ignoring the extreme folks, it accommodates those that love dealers and those that hate dealers.
I'm not sure how a hybrid set-up would impact haggling, which is prevalent in the auto market, but not in the MTB market. My guess is that it would even out. In my opinion, there are way too many factors that go into figuring out the price of a vehicle. That's why shopping around works. Every dealership is in a unique situation that enables them, or precludes them, from selling at a certain price point.