“After all BMW” What is BMW’s xDrive that led the world of electronically controlled 4WD systems? |MOBY [モビー]

BMW was more passive about 4WD than rivals

Tokyo Auto Salon 2023 BMW booth

Speaking of BMW, as expressed in the catchphrase “joy of running through”,sporty driving feelhas been cherished.

With a front engine ship and rear drive (FR) as its background, and a combination with a vertical inline 6-cylinder engine for many years, BMW is more passive than rivals Mercedes-Benz and Audi for 4WD. bottom.

While 4WD has excellent straight-line stability and running performance,There is a strong tendency to push under, and BMW did not evaluate it in terms of turningIt’s from

However, as 4WD systems for passenger cars became more widely recognized, BMW was forced to adopt them as well. We introduced 4WD models such as E30 type 325iX and E34 type 525iX.

Pioneer of SUV, X5 adopts passive 4WD


Initially, the 4WD system used by BMW was a passive 4WD with a ZF viscous coupling in the center differential. The drive torque is distributed in a FR-like fashion, front wheel 37: rear wheel 63. We were able to distribute up to 80% of the driving torque to the idling axle side.

The early model of the first-generation “X5”, which was the forerunner of SUVs (called SAV by BMW), was also equipped with a similar system (however, the drive torque distribution was changed to 38 for the front wheels and 62 for the rear wheels).

At that time, there was still a lingering scent of the off-road 4WD boom,Considering that the user’s usage scene is the on-road domain, such 4WD was used.By the way, most of this 4WD system was shared with Land Rover’s Range Rover, which was under the umbrella of BMW at the time.

The X5 is basically a model developed mainly for on-road use, but it is equipped with hill descent control in consideration of rough road driving such as snowy roads and unpaved roads. In addition, ADB-X (Automatic Differential Brake Traction Control) was also installed in order to improve the ability to run on rough roads, compensating for the weaknesses of the open differential.

Also, one of the topics was that the early Dynamic Stability Control (DSC), which prevents skidding by brake control, was adopted.

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