It would be cheaper to do nothing if that were true.
Then someone offers them $1 each for a fleet of 1M cars, who is going to turn down $1M for a few TB of data?
To your second point, surely they’ve considered the hit to their relationship with their customers before selling for $1/car. Surely the trust between them and their buyers is worth far, far more than that.
Even assuming maximum greed, is every car manufacturer really so short-sighted as to break that trust for so small of a return?
Rather than saying "give us 1$ and we'll sell you a customer's data" it was more like "provide the navigation software and we'll let you keep the data". It probably seems like an elegant solution: as long as the driver needs navigation they "pay" for it with their data. It's really no different from how gmail or facebook works.
something around 50% of Uber's profits now come from their "private" owned insurance Company. That, of course, does not have to disclose how they are making money. Even though Uber is their only customer.
There is probably some sort of similar deal happening here.
Selling it is pure icing on top.