Quincelady:

Hopefully, you have cured the water-in-trunk problem. If you still get condensation on the insides of the rear window and windshield, there are a couple of other possibilities.

First, if you are running the heat AC or vent and if you also smell antifreeze, it is possible that the heater core radiator, its fitings, or some hose to or from it may be leaking.

Second, if you smell a musty smell when you run the heat, AC, or vent, your drain hose on your AC condensor could be stopped up somehow, allowing water to accumulate in the AC drain pan last time you used the AC. This is usually an easy problem to fix once the drain hose is located. Usually, blowing compressed air up the hose or running a wire up it will clear the blockage. A friend with am MB had this problem. On another make, I discovered that the hose had actually moved in its mountings and become kinked, thus causing the stoppage. This was easy to fix be repositioning.

Hope this helps,
Richard