Its really not long enough to get all the damp out - Certainly hot air holds
more water vapour than cold, so its good to get the inside as warm as
comfortably possible, but equally important to get a good airflow through the
car at all times, hot or cold, to whisk away the damp air.
If you have aircon that drys the air and, even when cold, will help.
Don't use recirculate.
When you arrive at the destination, let the hot moist air out by leaving the
door open for a few seconds.
Do whatever you can to avoid bringing water into the car - damp raincoats /
shoes etc. - probably little you can do about this.
If parked under a carport or in a garage, leave a window or two cracked open a
touch if security is not compromised to allow air flow through the car.
Go for a long hot breezy drive once or twice a week to dry the car out.
Hope that helps,