What is the maximum safe storage temperature for a bike?
I've heard of tyres exploding if inflated close to their limit when cold, then left in a hot confined space. But unless you're running your tyres at 100 PSI and up, I wouldn't be too worried. But perhaps someone with more knowledge will chime in; I'm just hazarding a guess about that. I don't think there's anything else on a bike you'd need to worry about though, not as far as temperature goes, anyway.

Carbon fibre doesn't like UV. Most if not all carbon fibre products use UV-protective resins in their construction to avoid delamination from prolonged exposure to sunlight. I'd be a bit suspicious of cheap n cheerful carbon parts.

To be on the safe side, let your tyres down a bit and keep a white sheet over the bike when it's in the car. Probably a good move anyway; a bike is a good reason for a car thief to break in... it doesn't matter if your car's alarmed; they're stealing the perfect getaway vehicle!