I would say NTA. But I’m not surprised he was upset. If he participated in selling the old car with the expectation that the car you inherited was taking the place of the old car and would be mutually owned, it was because there wasn’t clear communication.
Regardless, he doesn’t get to make unilateral decisions with mutually owned property. So even if he thought the car was mutually owned, he can’t just make decisions that disregard your opinions.
That looks great