http://www.advantage-cfd.co.uk/News/...-Releases.html

from the splitter thread, but not a dead link

 

AWESOME LINK! wow. great stuff

 

Regarding the splitter issue, the most important thing is making sure the underbody diffuser is fitted to it and not higher up at bumper level.

Spoilers are efficent at 20-60 degrees.
They should be between 20mm and 160mm.
extending it down the sides of the vehicle seems like it would reduce the vortex it creates.
spoilers make the car much more aerodyanimc.
a spoiler at 0 degrees (like on the sport model) will create downforce and better cd because of the low pressure zone below it and that it causes flow to separate better.

Flat underbodies make a big difference.

Dual plane wings are much more efficent than single plane.
dont get too thick on wing thickness.
dont go too steep with the angle of attack.
dont have too much wing camber (curve).
wing endplates increase efficency some, but more area should be below the wing than above it.

its all about FLOW SEPARATION
keep it attached and direct it where you want it and you have a very aerodynamically efficent vehicle.
get flow to detach after the vehicle (as opposed to creating a low pressure zone behind the car and causing drag)


That about sums up the articles. They have lots of great charts and pictures so I suggest you read them all.