My husbands car smells like Mildew! It's so gross. His clothes stink from just being in the car.?

My husband bought a used car back in December & the car didn't have any odors except smoke. Summer rolled along and now the car stinks, bad. He keeps his car clean and I even detailed it for Fathers day. I scrubbed the carpets & seats with a carpet cleaner, vacuumed every nook & cranny in the car it was a very detailed job that I did seriously professionally done I spent hours on it. I cleaned the interior immaculately as well as outer. I thought after such a thorough job that the stench would be out but now with the heat its worse. I refuse to get in that car to go anywhere. I always want to take mine but when he takes his drives to anywhere and gets out his clothes smell!!! I can't take the odor of mildew. I ask him to strip off his clothes and shower up each time he steps back in the house. I know his co-workers have to smell it too and I don't want them to think that he has poor hygiene. It's almost like that Seinfeld episode of when Jerry bought the car that smelled like B.O...LOL