It could be a restriction thing that's what it was for my daughter she just got use to it

I've tried everything because my daughter was the same way and still don't like it at times. I found that if I feed her before leaving and change her diaper she's much happier. Then I play either baby Einstein on my phone for her or use the white noise app if she's sleepy and it works just about every time but I have to turn it on right before she hits fussy.

I have one of those mirror things and I put my phone in it and put on a YouTube sensory video when Dex is being super fussy. It always works.

My daughters are the same ! They hate the car seat && vehicle.

Its normal but try buying one of those mirrors you can put on the head part of the seat. Or a toy that hangs on his carseat