Our two car garage has too much stuff lining the walls to accommodate both large vehicles we own. When the second vehicle is needed for early morning transportation but is coated with frost that would take time to scrape off, my husband takes the first vehicle out of the garage, brings in the second vehicle and then plugs in the small space heater.
Within 15 minutes, no matter how bad the glazing of ice crystals, the vehicle is covered with droplets of water instead of frost. This way, no one has to stand outside in the cold to scrape but both of us have vehicles we can just get in and go!