Car sales in the US is not a useable example for any microeconomics discussion, let alone (notionally) generalized principles. Car dealers are one of a handful of infustries with an explicit exemption from federal antitrust law prohibiting price fixing and collusive monopolies. So, they made those, decades ago. And abuse them constantly.

The way you can tell this is true is price any car or truck in the US for sale from dealer X. Then attempt to shop around for a better price from set of dealers Y-Z. You will find that within a convenient-to-you radius the same regional dealership operating co owns all of the dealerships for your preferred make/model.

Then if you expand your search radius you will find that opco is owed by a larger holdco, which "oversees" supply and demand so your price. Not a free market. And not the manufacturers' doing, or their input suppliers, or inflation. It's a gov policy choice as abused by nearly a century of lobbying which some might call bribes.

As I recall the other US industries with explicit antitrust exemptions are Major League Baseball... and domestic shipbuilding vis-a-vis domestic maritime commerce. This is famously why the Love Boat *had* to go to Mexico, because it was (presumably) foreign flagged and couldn't move between US poets without calling at a foreign port.