As you said, Larry, if the instrument warms up too quickly, you will get moisture (condensation) and that can cause problems.
I never leave my keyboard(s) in the car, regardless of the weather.
That's why I bought/use a lightweight instrument...so I don't mind moving it.
This is coming from a very lazy guy.
Ian
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Yamaha Tyros4, Yamaha MS-60S Powered Monitors(2), Yamaha CS-01, Yamaha TQ-5, Yamaha PSR-S775.