Just bought a car which has not been driven and stored inside a garage for several years. How do we fumigate and clean the interior? Part looks like it is leather and part vinyl since some areas have severe mildew (or mold?) and others are untouched. The smell is unbearable at this point. It is a 2004 Toyota Avalon LX and is in like new condition on the outside.
I've had luck cleaning Mouldy Vinyl with scrubbing bubbles spray.
My car is also trashed, and has cheap vinyl inside, and I haven't had much luck cleaning it. Your best bet is to get the vinyl replaced, because it will likely crack or go brittle soon.
As far as fabric goes, most supermarkets sell those powerful steam cleaning units, get one of those, and they work amazing for cars. It's good for cleaning out the unidentified human slime from seats.
If you are not able to get it clean enough by cleaning, you can probably pick up a complete used interior of the same color and swap it out with yours. Considering what you are getting, it shouldn't be too expensive. There may be no other way to get the smell out of the car otherwise.