When weatherstrippingthe rubber seals that keep water and air from infiltrating the cabin through the doors and the trunk lidstarts going bad, that rain eventually ends up on your seats, floorboards, carpet, and trunk. Sometimes when weatherstripping fails, you'll find a slow leak that can cause water accumulationcars have been known to end up with a wading pool where passengers' feet should go. The good news is that identifying problem seals isn't very difficult and neither is replacing them, although it can be a bit expensive.
Finding a seal breakdown might take some detective work. Just because you find wet carpet in the rear passenger area doesn't mean the failure is in the rear passenger doorwater has a funny way of sneaking around in a car. The wind noise you hear while driving is a good indication of the source of the leak; follow it to narrow your search. Inspect the seals around the doorframe and the perimeter of the door itself. Many times you'll find that the seals have cracked with age or that a hole has worn through from use. Sometimes the rubber will have lost its pliability and can no longer do its job. Check by squeezing it between your fingers; if it doesn't squish or spring back, it can't make a proper seal. If you're having a hard time pinpointing the source of a leak, run water from a hose to find it.
Once you've found the problems, you have several ways to address them. Really enthusiastic owners will see bad weatherstripping in one part of the car as a sign that all of it is failing and will replace all the stripping as preventive maintenance. Frugal owners will fix just the problem areas, and that's fine too. Cheapskates will break out the silicone sealant or duct tape; this is not recommended.
Weatherstripping comes in two varieties: factory-replacement and generic. Generic can be a little sketchy and is best suited for a very old car or junker you won't be keeping long. If you want a proper fix, and judging by your pride in ownership, you do, factory-style replacement is the only way to go. Cross-shop your VW dealer against aftermarket retailers to find replacement parts you're comfortable with. Most of the time aftermarket replacements are just fine, but it's up to you. Before you start ripping stuff out of the car, though, compare new pieces with what you're replacing to make sure they're all the same size, with appropriate cross sections, holes, and joints.
If there are any screws holding the old pieces in place, take those out first and set them aside for reuse later. Peel away the stripping; be sure to remove the adhesive layer holding it on. You may need to use an adhesive remover to get it all. Next, wipe the weatherstripping channel and the new seals with a gentle cleanser and towel them dry; they may still retain a bit of mold-release agent. Apply a very thin bead of weatherstripping adhesive (available at auto parts stores) to the channel and install the seal lightly at first. Be sure everything is properly aligned, then press the stripping firmly into place, ensuring good contact with the adhesive. Replace any screws and allow the adhesive to dry as directed. This should solve your whistles and wetness and prevent any undue carpet sogginess in the future.
