My friend DickieT, some years ago left his Technics KN800 in the trunk of his car for a couple of days. The case melted nearly totally. It was unusable. I suppose more modern materials would hold up better, but since that time I've never left my kb in the vehicle in the heat OR cold.
Usually I play at least 3 outdoor parties each year, Memorial Day, July 4th and Labor Day. This year the first two were canceled because high water damaged the venue. Maybe it will be ready by Labor Day. They have a shaded cover for me, and a huge fan to blow away heat and "skeeters". There is usually a somewhat cool breeze blowing off the lake. It's one of my favorite jobs ever. Great barbeque with all the trimming and a plethora of homemade desserts. Frozen beverage either with or without alcohol are available from a dispenser. Too notch. And they even PAY me to come!