I have watched a lot of wind tunnel testing at work
and seen my problem when I hit 130 mph. at that point
the rear of my car started lifting off the ground..
the rear spoiler/wing made a BIG difference... it made
the car stable and picked up 3 mph with just the wing..
I was spinning on top end but didnt know it till
I lost control with a 15 mph head wind(which just
adds to what your car thinks its going)... but my
car is a hatch back with a short trunk area... it was
sucking the car upward... non of these cars were
tested above about 120 mph... thats the reason all
of the prostocks and other QUICK cars test in the tunnel