[s-cars] Xi, 4Motion, 4matic

[Keith Maddock]

Kevin Campbell <kevin.campbell at autodesk.com> wrote:
> Does BMW, VW, or Mercedes use audi's Quattro all wheel drive system on
> any of their vehicles?

The only other non-Audi to use the Quattro system are the current
generation Passat vehicles, marketed as "4motion", as they are based
on the A4 platform.

VW's 4wd system for the past several years (and into the future as
well) is based on the Haldex coupling.  The upcoming Passat
replacement will be based on a VW rather than Audi platform and will
also have Haldex.

BMW has been using two AWD systems.  The early X5's and AFAIK to date
all 3 series iX vehicles have used an open center differential with (I
think) a fixed 38/62 F/R torque bias.  The latest iteration of the X5
and the X3 use a electronically controlled coupling - I think I've
read this will end up in the next 3 series iX products.  This is a
nice system as it is integrated with the stability control to
progressivley couple/uncouple the center coupling to influence
understeer/oversteer in the region of 50-105% of "the limit".

To the best of my knowledge, all Mercedes AWD products (save the
G-wagon) use an open center differential with (I think) a fixed 40/60
F/R torque bias (like some BMW's).  ML-class uses a 48/52 F/R bias.

In the open center diff applications, the brake-TC is used (like EDL
on the UrS6's) to handle slip (by absorbing power rather than
transferring it)  in conditions where the fixed f/r bias is not
optimal.

Cheers,
Keith