I want to open the door by myself!

Enoch has been buckling himself into car seat since he was about 2.5 years old which is really advanced for his age. Recently he wanted to open the auto car door by himself. I told him that if he can unbuckle himself from the car seat then he can open the auto door by himself. So today he refused to get out of his car seat and wanted to unbuckle himself. I unbuckled him twice but he buckled himself back up. And even after we all went inside the house, he still set in the hot car for about 10 mins trying to unbuckle himself. Of course he is too young to do that, eventually I asked him if he wanted to go inside the house. He said yes, but not willingly. He was super sweaty when he finally got out of the car. He still cried for a good while for not being able to open the door by himself. I'm just glad that he went inside before he got too hot and die. Sometimes Enoch is really determined or stubborn, which can be a good thing. I just hope that when he grows up, he will still be so determined to do things he really likes and not easily give up.