I have to keep my car outside for the UK winter so I installed a cheap de-humidifier from Amazon about £30 $35.
Ran a cable in through the trunk to an outlet behind the back seat.
Now HERE IS THE TRICK These piezoelectric dehumidifiers don't work below 15 deg C ..Ice forms inside and that's it so I fitted a timer 45 min ON and 15 OFF ....ice melts when its OFF and drops into the tank.
Removes about a cupful in a couple of days...