I agree. If it was a 'flood car,' ie: where the interior was fully soaked, the only treatment is to completely remove the interior carpeting and seats...all the lower trim might not be a bad idea either. As we all know, water gets everywhere.
It might be possible to spray the carpet backing with an enzyme type cleaner to kill any mold before it has a real chance to get a grip on the area and use a mild bleach mixture on the metal floors.
On cars where I have shampooed the entire interior and really needed to speed up the drying, I've used a regular household dehumidifier set on the floor with the extention cord either rolled up in the window or closed in the door to seal off the interior while the dehumidifier does its job. If it's a car with a large rear storage area (SUV, station wagon) the rear compartment will hold the unit perfectly. Or if the interior has been removed, the unit fits nicely on the floor.