...a cement floor at all.

A cement floor is pretty good on providing a stable clima which will help to prevent the car from rusting.

If you close the porous floor the moisture from a wet vehicle will not be absorbed.

A perfect place is a garage with a cement floor, lots of air movement and a stable, rather cool temperature.

A heated garage with closed windows and coating on the cement will kill your car within just a few winters.

A garage floor is a workplace. I'm not going to eat from it. Usually

Kind regards
Eberhard