Garage floor advice

I put plywood under the cars in my unheated barn with concrete floor and run a box fan to circulate air under the car on my 14,900 mile 1981 Imperial

Read somewhere just this week about putting plastic under the car. Might be best to put plastic down then plywood on top of that.

The plywood idea came from a Chrysler engineer after seeing his 63 Sport Fury sitting on wood in his garage.

The box fan from seeing a guy store his 442 in unheated garage.

Last winter I never seen any condensation on the cars, UNTIL I got the dart out one day in the spring and when it was in the driveway seen condensation on the wheels, AFTER pulling out of the barn.