[ChainOfFools]

Conditions may be different now, with the internet at all, but the fact is this has been tried a number of times by individual dealers, and at least in one very large scale circumstance that I can recall - the now defunct Saturn division of GM. Saturn famously touted fixed, non-negotiable sales prices as a feature of their vehicles, part of the total package of the car similar to its warranty and so on.

Even with all of the might of GM behind it, and with the cars themselves having a distinct position in the market with a few unusual features no other brand had, such as polymer body panels that were lightweight, rust proof and easy to repair (by simply replacing entirely), Saturn only lasted a few years before folding.

I was selling cars myself for a few months during their peak, and recall that they mainly got used as a rhetorical backstop by customers who would bring in an invoice for our vehicle (printed out from edmunds.com, which had just barely become a thing at the time), and argued that they should pay some absurdly small fixed number ($100, $300, possibly $1000 if they were buying an NSX, our "halo" vehicle) over invoice to get a fixed price like saturn.

This was a couple years before dealerships had organically responded to the internet by adding all sorts of hidden costs that do not show up on an invoice to the base price (in addition to the usual ones) so unlike today the invoice was literally our invoice price. But they were not there to buy a Saturn they were there to buy a different brand of car.