Are there either any supercars or tuned sports cars with Nascar style passive flaps for safety?

[ame="http://en.wikipedia.org/wiki/Roof_flap"]Roof flap - Wikipedia, the free encyclopedia[/ame]
HowStuffWorks

AFAIK the closest things are the Pagani Huayra active flaps.

Being passive the Nascar flaps can be retrofitted into almost any car.
Maybe autobahn tuned German cars will lead?