I agree with you that most(probably all not walking into a CarMax) people who walk into dealerships today attempt to negotiate. I agree with you that they are unsure if the hours and hours they spent online researching have led to the best value in the market. I agree that they use negotiation as a way to ensure they aren't overpaying.
My opinion is that if you negotiate with a customer that is in your showroom looking at a specific car that they already viewed online and determined was a good deal you are simply giving gross away.
The problem is that going to a one price philosophy is hard. Frankly while most people will say that it promotes an "order filler" mentality it is actually much more difficult to sell in a one price environment. It is a lot harder to continually defend market pricing and your value proposition than to reduce a price by $200.
This is what CarMax has done better than anyone in the game hands down. They have built a brand that customers believe is different. Customers are not buying a car they are buying a CarMax car. They do not attempt to negotiate because:
1) they know through tireless commitment and marketing CarMax doesn't negotiate. Most will tell you that they came there because they knew they did not have to negotiate.
2) they have bought into the total value proposition. 125 pt inspection; 5 day money back guarantee; no frame/flood damage or major title disclosures.
It takes consistent messaging and commitment. It will most likely cost you a few deals here and there. However I bet over the long haul you get better customer experience because they do not feel like they have to negotiate to get a good deal and you will be saving gross because of the multitude of deals you didn't give away that extra $200 on.
