[Wonderbar]

Originally Posted by mad_sb

Autospeed has a lot of good articles on budget aero testing, you do not need a wind tunnel. Air pressure measurements, for example, can be taken from the void area (between the trunk pan and where the diffuser would be) before and after... a reduction in pressure with the diffuser should indicate a reduction in lift if i am not mistake. You would certainly want to confirm it is not catching additional air at high speed causing parachuting, this i think would show as an increase in air pressure.

You can also use linear potentiometers on the rear shocks (or any two points between the chasis and the control arm) to measure average ride height differences at speed.

Lastly, as you mentioned, the mpg figures (if measured accurately enough) should be able to show a reduction in drag if one is present.

Agreed on all, I plan on a coast down test as soon as I get some time. Air pressure testing should be easy enough. It comes down to time.