I once parked my 300D on a nice sunny afternoon under a lovely oak tree. I left the sunroof open. I came back to the car to find that a broken sprinkler head was spraying a thick stream of water about 15 feet in the air, and the downfall was CENTERED in the sunroof opening. I measured 4 inches of water in the back floorboards! Driving was a nightmare, especially when I had to hit the brakes and a river flowed through the car. Anyway, I took it to the neighborhood car wash. The vacuums there are wet/dry vacs. Cost a few dollars, but sure did get most of the water out. Good luck!
88 BMW E32 735i (make it go away)
95 Volvo 960 "Inga" (valve problems)
95 Nissan Maxima (the indestructible)
89 Ford Ranger XLT (ugliest truck in the South)