Average is over 12 years [1].

[1] https://www.reuters.com/business/autos-transportation/americ...

Cars are often sold. If everyone knows that nobody will buy it in 15 years, the person buying it in 12 years will pay less, which means the person buying in 9 years pays less, etc, so the person buying new doesn't recoup as much and has less to spend on a replacement.

That doesn't seem true. I'm seeing 6 to 8 years, with the average car age being 12 years old. Resale value is important.

No reason a car can't still be on the road 100 years after manufacture

> Most people own a car for 3 years or less

This seems absurd on the face of it.

I never bought a car newer than 15 years