Getting Rid of Mildew Smells

I have heard just leaving the windows open on the cold windy winter day will help, weather permitting. My Dart had sat for many years, the mice decided to move in and build condos using the material from my headliner insulation. Used varies spray cleaners and vacuumed but little could be done with the lingering smell. Made a trip to smoke shop and pick up some incense put some sand in a coffee can for the sticks and let it burn, had a smoke filled car. After a few sessions all was well, cover a stink with a stink............