I would love to get mine to go down all the way, too. But AFAIK it is physically impossible for all the glass to fit in the door due to the angle of the doors. That's the explanation I heard in the past, but I'm not sure if that's true.
It is impossible, due to the design of the rear wheel well. The only car that I know of that does this is the old Maximas by tilting the glass forward and leting like 2" stick up on the front side. If we tryed to do this it would probably break within a week. If you are an expert and can get in there, I know I can't, feel free to experiment. Good Luck. Also, the new Sienna minivan does it. Kinda cool feature, but impossible on most cars.