Can they go down any further than midway? If so, how?
Our SAAB is the same way. If you examine the shape of the rear doors, you will see that it would take a very special window to be able to go down fully.
I was surprised by the lack of opening as well. Our '09 Jetta with a smaller back door and larger extension into the rear fender still had a better opening distance. The Passat is a little disappointing in that area.