To get rid of dead mouse smell in the car, the first thing to do is get rid of the dead mouse. Once removed, the dead mouse odor can last for several weeks. No matter how many scented candles, air fresheners or bags of potpourri you have kept in the car, this is just not enough to get rid of the hideous smell. These might mask the smell of the dead mouse temporarily but for a permanent solution, you need to do more.
Remove the dead decaying mouse from the car. Wear protective gear like gloves and a HEPA mask as the dead rodent may carry diseases.