The "position of the vertical wheel plane"? Yeah, in the...
...fore-and-aft direction, to be precise -- the vertical is also "perpendicular to the axle", but that is handled by the springy bits of the suspension. :-)
Like Greg says in the great-grandparent post to yours, "thrust" implies that it's pretty much parallell to the long axis of the car, to transmit the fore-and-aft forces from the drivetrain and brakes. (And I *think* that's what it looks like in those BMW pics you found.)
That's a "multi-link" suspension, the even-newer development from the "double wishbone" suspension, where one or both (usually just the lower, I think) of the A-arms has been replaced by two or more separate simple rod-shape arms; kind of like picking the "A"- or "wishbone"-shaped arm apart into two: A -> /\\ .
So it seems your A8 has multi-link, not actual double A-arms.
[link|mailto:MyUserId@MyISP.CountryCode|Christian R. Conrad]
(I live in Finland, and my e-mail in-box is at the Saunalahti company.)
Ah, the Germans: Masters of Convoluted Simplification. — [link|http://www.thetruthaboutcars.com/?p=1603|Jehovah]