I never leave my gear in the car, especially during cold weather, which is most of the year here in Cape Breton...it's only 4 degrees above freezing here today.
I'm lucky, as my gear travels in my Honda Accord, and the back seat is folded forward, allowing heat to get into the trunk...the keyboard is in the car.
Always give your arranger time to acclimatize itself to the room...condensation can form, giving problems.
Ian
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Yamaha Tyros4, Yamaha MS-60S Powered Monitors(2), Yamaha CS-01, Yamaha TQ-5, Yamaha PSR-S775.