My little guy has been crying non stop whenever we have him in the car seat. He used to love the thing, now loathes it. We've adjusted it and done everything possible to make him comfortable. Whenever we take him out he's drenched in sweat. What do I do?! We have a long car ride coming up!
My first kid loved the car and his car seat, my second child not so much. You can try dressing him in super thin clothes, offering toys or even something hanging from the seat for him to look at but that's about it.
My daughter gets really warm, too. I assume you dress him as lightly as possible. You could sit back there with him and use a little handheld fan on him to keep him cool? I try everything, too, but once my daughter gets going she's gone. I think feeding her might help, but I breastfeed so it'd be awfully hard to lean over her car seat with a boob.
Re: Car rides = HELL
My daughter is still fussy in the car at 14 months old. It sucks.