Well, technically minimum advertised price is something that is on-the-border legal. There are several rules set by the FTC and one of them is anti-price fixing to ensure that free-market forces will be able to prevail.

The way most manufacturers get away with it is that resellers are "strongly" encouraged not to advertise lower, but with the Internet, vendors get away with it anyway. B&H Photo for example in NYC, they don't advertise the price, but put a button where if you click on it, they will email you the price.

You're right about manufacturer-owned dealerships, those aren't really going to work either, and they also might get into anti-trust laws if they try too hard to force indys out in favor of their own lots.

What might evolve is the concept of Internet car sales, where all you ultimately need is a place to pick up the car and this place is the same place that preps the car and does your after-sales maintenance.