...and radiused transitions, yes?
FYI, the bottom of my prototype tail went from 4 degrees at the back of the car to 6.5 degrees at the end of the tail, and the flow under there was attached but really turbulent, even with a smooth belly pan. I'll be surprised if it stays attached at 15 degrees!
from:
http://ecomodder.com/forum/showthrea...tml#post156960