In the iDrive, you can regulate how much heat goes to the seat back and how much goes to the seat bottom. I'm sure you knew this, but just in case. There is so much to know about this vehicle that sometimes a reply like this could help.
In the Garage:
2001 330xi Orient Blue on Gray
2006 M5 Interlagos Blue on Black
2008 X5 Space Gray Metallic on Black