I mean piracy would be making a copy of the car and keeping that (which is different from stealing the rental car)

He probably thinks that if he takes the car it denies someone else the ability to use it. Do you see how that is different? If you pay the full price for the car there is no expectation of shared use and you can take it apart and change out the parts or drive it off a cliff if you want. Most modern software has Eula restrictions on what you can do with it and you pay for a lifetime despite your use not at all restricting the use of the software by others.

"You wouldn't download a car"

Depends on what the understanding is when we exchange money for a digital good. If we agreed that I can own it forever but you then pull the rug out from under us, then there's an argument to be made.