what's this thing?

[GasSavers_rav]

Have seen it on newer BMW's and audi's
http://cgi.ebay.com/ebaymotors/04-05...3286.m20.l1116

Its the one behind the spolier, is it some type of a VG?

[GasSavers_Diemaster]

most of the time thats a GPS / XM etc antenta. they mount the antena on alll cars but if u want XM for ex then it gets hooked up to the XM box. otherwise it's not conected.

[lunarhighway]

just a fancy looking antenna.... probably low drag but no benefit adding it if you don't need it imho.

[GasSavers_rav]

thanks for clearing it up.

[Nerds laugh at me]

If you look closely at it, you might notice that the shape is a perfect Vortex Generator.
It functions as an antenna, but I'll bet that it also helps as a VG.