If mice get into a car, they may leave behind an unpleasant odor. Even if no mice have died in the car, their urine and feces on upholstery can make the whole interior reek; this odor may linger for a long time. Not only is the odor unpleasant, but mouse droppings may spread hantavirus disease. Disinfecting the upholstery, therefore, needs to be the first step in the cleaning process.
Put on rubber gloves and mix a concentrated household disinfectant liquid in a bucket with water, according to the label directions.
Wet paper towels in the formula, as suggested by Environmental Health & Safety Online. Use these to wet areas on the upholstery where there's visible mouse urine or feces; throw the used towels away.
Wet a sponge in the mixture. Sponge the disinfectant over the upholstery and the carpeting to saturate it with the mixture.
Roll down the car windows and allow the carpet and upholstery to dry completely. This will take several hours to more than a day, depending on the weather.
Sprinkle baking soda, as suggested by CarSpace, over the upholstery after the upholstery has dried. Use a dry sponge to spread it over the upholstery and leave it overnight.
Vacuum the upholstery the next morning. If any odor remains, either repeat the baking soda procedure or spray the car's interior with a commercial odor neutralizer.
