Am I in the wrong?

Okay so I basically have 2 cars now. My first car was corolla but since my partner and I moved in, he’s been using it since he doesn’t have a car and his job is farther (my mom can give me a ride to my job). He uses it 5 days a week and even claims it’s more his car. I got tired of not having my own car (+ he broke the handle on that one and also has more issues) so i was like i’m going to get myself a new car for the kids and I. So I did. I got it last week and installed the car seats. Well my partner does laundry every weekend. My brother is coming over and we want to go to target. He got mad saying I know he has to do laundry and I told him take the other car. He started complaining saying it’d get too hot and didn’t wanna die (the ac broken). Then he said if my brother is coming why don’t we take his car and I told him I don’t want to move the car seats. Now he mad and saying he’s not going to do laundry. I just feel like that’s dumb because it’s MY car. I mean I know both are but I basically gifted him the other one. Like I got myself a new one so each would have our own but now you want to take over my new one?? like am i wrong for expecting him to use the other one?