There was a promo last year, if you were LH SEN you could apply for SIXT Plat. I am sure you can also try via Amex Centurion Service.
Link:
http://www.flyertalk.com/forum/Forum32/HTML/001738.html
I just asked them for a VIP arrangement for DTM (Deutsche Tourenwagen-Meisterschaft) in Hockenheim, let use see how they perform
(edited to add the link)
[This message has been edited by Uli (edited 01-25-2003).]