Baby sweating in car seat

My son has started tolerating car rides and the car seat better. But I'm wondering if one of the issues might be that he is getting hot and sweaty in it.

I was driving home last night though and again he was crying almost the whole way. I know he was tired because he hadn't slept much all day, but when got home and I got him out, his back was all sweaty. He was just in a short sleeve onesies and a thin woven long sleeve shirt. It was like low 40s/30s here.

Anyone else have this issue? I don't want to have to get a new car seat, but if that would resolve the issue, I will. Him getting sweaty and wet and then being out in the cold is not going to be a good combo either.

This is the car seat.

**This isn't the first time he's been sweaty coming out of the car seat, even if he hasn't been crying. He's been a sweaty little man from day 1 lol.