Why does your car still smell after you left the windows down all day? Because the odors have settled into the upholstery and carpet, so each time you step in and sit down, they are released into the air all over again.
Eliminate these odors by filling a saucer or small bowl with vinegar and placing it on the floor of your car overnight will remove odours from your vehicle. The vinegar actually absorbs the smell. It has also been said that ammonia will do the same, especially nice if you can obtain a scented brand. Make sure that you keep young children away from the bowl or saucer.