Interesting articles on racing aero
 

I don't know if these have been posted before but I found them interesting and helpful.
Car Aerodynamics - Hot Rod Magazine
Aerodynamic Tips and Tricks You Can Use for Better Performance - Hot Rod Magazine

I wouldn't go to the A2 tunnel if it was me however. The tunnel looks very small for a full size car. The blockage ratio looks very high and won't yield to great results. Also it isn't a rolling road tunnel. The rotating of the wheels have a huge effect on the cars aerodynamics.