If you look to the following pictures (although they are not probably the more up to date ones) it seems that top wishbone attachment is slightly higher on Audi R18..
http://www.nikeride.com/pics-aplenty...i-r18-photo-2/
http://www.mulsannescorner.com/AudiR...ns2011-MF2.JPG
http://www.carsendse.com/2011/03/201...di-r18-rear-2/
Maybe not a huge difference, but still something.
Don´t know if they use a low gearbox like williams. But sure they are at least sacrificing suspension package more than on the R18...