Well, it’s very hot out right? 4th of July and all. So on a hot sunny day, leave the car outside, all windows open, and let it cook in the hot sun. You could put a fan in the window and blow air through the car from one side to the other too, might help even more. To kill off mold you want to elimate all moisture you possibly can. Then use a strong shop vac and vaccum everything in sight. Finish up with a general cleaning of the hard surfaces using a compatible cleaning product. It might just do the trick. This would be all but impossible to do in the winter, but in the summer it just might work.
One more thing. There’s some possiblity there is water (and mold) inside the doors too. You may have to open them by taking off the inside panels. While they are open, clean it out the best you can, and make sure the drains at the bottom of the doors are not plugged. Don’t re-install the panels until everything inside the door is absolutely dry and all debris has been vacuumed out.