This is great info.

I wonder what the effect is with windows wide open? How much more of a hit that is, than the 6" that Kate tested?

Speaking of windows open -- has anybody noticed how unbearable it is to drive the HCH at highway speeds with just the back windows open (all the way)? It sounds like the car is going to burst. Spooky. The only way to offset it is to open the front windows a bit also.