Martin, Giannis et al.
Would you be so kind & comment the AWD system BMW have introduced in Active Tourer
Phew, EnI, this was a tough one to unpack with absolute clarity and factual accuracy - and I still don't have all the facts. Sorry but time doesn't permit much these days. I spent a little time over the weekend and can offer the following:
In brief summary:
The AWD mechanics / supplier info of transverse xDrive in the 2 Series Active Tourer is not readily available on the web, so I cannot comment with any certainty on this product as yet.
In answer to a) MINI ALL4 AWD engineered and supplied by GKN - a Japanese firm who acquired Getrag's Driveline business - this electro-mechanical system features a rear-mounted center coupling; defaults in 50:50 torque split mode from start up but then bleeds torque away from the rear axle at higher speeds to facilitate fuel economy.
Maybe Active Tourer makes use of this new AWD system?
http://www.gkn.com/driveline/technologyandinnovation/Pages/disconnecting-for-fuel-efficiency.aspx
http://media-centre.gkndriveline.com/drivelinecms/opencms/en/media-centre/news/gkn-news/article_0041.html
For b) Haldex Gen V - Haldex is now a wholly owned subsidiary of Borg-Warner and this electro-hydraulic-mechanical coupling, located at the rear axle, is an on-demand AWD system - much as before with previous generations - in which the system defaults to FWD with a small amount of "pre-charge" torque residing at the rear axle. The unit is more compact and quicker reacting than before. When slippage at the front-axle is detected, or a demand for torque is required, then the coupling sends drive to the rear wheels. This Haldex V coupling can apparently be adjusted now to default a greater apportionment of torque to the rear axle via a driver selectable option as evidenced by the new TT Mk3 generation.
For c) The ProActive coupling in the MFA-based AMG models is engineered by Magna on behalf of Mercedes Benz. It is very similar in its operation to Haldex V in that it too is an on-demand AWD system. See:
http://www.magna.com/investors/press-releases-news/news-page/2014/06/04/news-release---magna-supplies-awd-system-on-mercedes-benz-gla
So, what does this mean from an overall technology perspective? Well, at a detail level - quite a lot; and from a high level - not so much.
Sadly, the days where the mechanical attributes of an AWD system had a distinct and tangible outcome on the driving experience are all but gone. It's all down to software programming and calibration now - especially for the systems listed above.