I've got my boards and kit always crammed in the car, winter or summer. No issue so far. Until yesterday, 25kn day, head high waves, beautiful... took my favorite board out and couldn't believe what I saw: it was twisted along the longitudinal axis by as much as 2". Weird. It's a rather flat epoxy board. Or it used to be rather flat
No signs of cracks or delam, it looked perfectly OK apart from being twisted like a potato chip. I guessed it was the heat in the car and the kites crammed putting pressure on the board. So, if the heat in the car is enough to twist it, I will use heat to twist it back. Clamped the board down, pulled a strong plastic sheet over it to make sort of a tent, heated it up with a hairdryer for an hour, and alas: the clamps pulled the board back straight. Let it cool down for half an hour, done.
Just wanted to share that trick with you. Easy enough and worth a try before you throw the board away.