Ok, until today I had not experienced this (Because I had not tried this configuration yet), but tell me if you have. At 50-55 mph, I lowered the rear windows, and the most god-awful buffeting happened that hurt my ears. It is a pulsing sensation that leaves my ears rigning for a few seconds. When I lower all 4 windows the nasty pulse goes away. It's almost like I need the rear gate window to crank down a bit to release pressure in the cabin if that makes any sense.