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25 years of BMW all-wheel-drive
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25 years of BMW all-wheel-drive expertise.
(Short version) ............................................................................................................................ 2
Variable distribution of power, wide range of applications:
The history of all-wheel-drive models from BMW. ............................................. 7
The intelligent route to increased driving pleasure:
Development and technology of the BMW xDrive
all-wheel-drive system. .................................................................................................... 12
The current range of BMW models with BMW xDrive. .................................... 18
25 years of BMW all-wheel-drive
(Short version)
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The road heads inexorably into the distance, rising steeply time and again.
Fortunately, the intelligent BMW xDrive all-wheel-drive system is in place to
transfer the necessary propulsion to the ground. 25 years on from the market
launch of the first all-wheel-drive model from BMW, the world’s most
successful premium carmaker has secured itself an outstanding position in
the market for all-wheel-drive vehicles. One in four BMW cars sold around
the world is now equipped with xDrive, the sustained success of the
BMW X models playing a pivotal role in this development. In addition, the
number of cars from other model series specified with all-wheel drive is
steadily rising. BMW currently offers 45 models in which xDrive provides
variable distribution of drive between the front and rear wheels. These models
extend all the way from the BMW X models via the BMW 3 Series and
BMW 5 Series ranges to the BMW 7 Series family of luxury Saloons.
1985 saw all-wheel drive offered for the first time for the BMW 3 Series –
both as an extension of the model range and as an alternative to the
customary BMW rear-wheel drive. By now BMW was using the transfer of
power to both axles not only to optimise traction on loose surfaces and in
adverse weather conditions, but also to enhance dynamic performance
though corners. The latest version of the BMW xDrive all-wheel-drive system
rises to this challenge more effectively than ever. Linking the all-wheel-drive
system up with Integrated Chassis Management (ICM) means that all
situations on the road can be recognised and evaluated to allow the
necessary control interventions to be made at an early stage. These can be
carried out by xDrive either on its own or in combination with Dynamic
Stability Control (DSC) or Performance Control. The power is distributed
quickly and with great precision to where it is needed, ensuring that the driver
enjoys the handling characteristics he would expect from a BMW – even
under extremely dynamic cornering.
In contrast to other manufacturers, who use all-wheel drive principally to make
up for the shortfall in traction suffered by front-wheel-drive vehicles, BMW
tunes its xDrive system to provide handling typical of rear-wheel drive. Even
in normal situations on the road, all-wheel-drive BMW models send the lion’s
share of drive to the rear wheels, the same place where the brand’s cars with
only one driven axle turn power into optimum dynamic performance. This
ensures that the hallmark BMW steering precision is virtually free from drive
forces in all-wheel-drive models as well. Indeed, all-wheel drive actually
enhances the driving experience through corners. In order to enable
particularly precise turn-in and a high level of directional stability, the latest-
generation xDrive sends more drive to the rear axle on the way into corners.
And that takes the brand’s characteristic driving pleasure to a new level
once again.
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All-wheel-drive technology from BMW: rigorous further
development, dynamic growth.
Over the last 25 years at BMW, all-wheel drive has developed from an option
initially limited to selected models to a growth driver for the ongoing
expansion of the model range. At the time it was launched in the second-
generation BMW 3 Series, all-wheel drive was offered exclusively in
conjunction with a 2.5-litre six-cylinder in-line petrol engine producing
126 kW/171 hp. Today, xDrive can be specified for the BMW 3 Series in
tandem with any of three six-cylinder petrol engines, a four-cylinder petrol
unit and a six-cylinder diesel powerplant.
The permanent all-wheel drive of the BMW 325iX unveiled in 1985
channelled power to the front and rear wheels at a constant 37 : 63 percent
split. Visco locks in the transfer case and final drive took their cues from the
difference in rotation speed between the front and rear wheels to provide
virtually fixed connections if required, and in this way optimise traction and
driving stability. From 1988 customers could also order a Touring variant of
the BMW 325iX.
Three years later came the arrival of all-wheel drive in the BMW 5 Series,
accompanied by the debut of electric control systems governing the
distribution of power. The newly developed system had multi-plate clutches
which could be controlled automatically and continuously to vary the usual
distribution of drive in normal conditions – 36 : 64 percent between the front
and rear wheels – as required. Initially, a hydraulically controlled multi-plate
clutch was used at the rear axle, but this was later replaced by electronically
controlled brake inputs. The control unit of the all-wheel-drive system took
into account wheel speed signals from the anti-lock braking system, the
rotational speed and position of the engine’s throttle valves and the status
of the brakes when analysing the driving situation.
From the outset the all-wheel-drive system of the BMW 525ix – fitted with
a six-cylinder petrol engine developing 141 kW/192 hp – proved to be
a superior concept to that of its competitors. The electronic control system
allowed extremely rapid and precise reactions, which also led to neutral and
safe handling characteristics in tricky conditions on wet or snow-covered
roads. The first all-wheel-drive BMW 5 Series was available in both Saloon
and Touring guise.
The creation of the Sports Activity Vehicle (SAV) segment opened up totally
new dimensions for all-wheel drive. BMW caused a sensation with the
introduction of this innovative new vehicle concept in 1999.
The BMW X5 captured the imagination of its customers with a level of
dynamic performance unmatched among its off-road peers. The
characteristics of the BMW all-wheel-drive system also served this set of
priorities. In normal driving conditions, engine power was distributed at a ratio
of 38 : 62 between the front and rear wheels via a planetary gear set, while
the standard-fitted Dynamic Stability Control (DSC), Automatic Differential
Brake (ADB-X) and Hill Descent Control (HDC) equipped the BMW X5 equally
as well for sporty driving as for challenges off the beaten track.
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Innovative vehicle concepts and xDrive give BMW the edge.
Since the SAV concept successfully established itself in the shape of the
BMW X5, BMW has been constantly building on its stand-out position in the
all-wheel-drive vehicle market through the introduction of new models and
the further development of its drive transfer system. All-wheel drive was
made available for the BMW 3 Series once again as early as 2000 – this time
in conjunction with two petrol engines and one diesel unit.
In 2004 BMW picked up the pioneering baton once more when it introduced
the SAV concept into another vehicle segment. With more compact
dimensions than the BMW X5 and even more agile handling, the BMW X3
was likewise very much one of a kind and indeed remained the only premium
model in its class for a number of years.
BMW also stole a march on its competitors in the development of all-wheel-
drive technology. The newly developed xDrive all-wheel-drive system,
introduced for the BMW X5 alongside the launch of the BMW X3, boasted
an extremely fast-working, electronically controlled multi-plate clutch in the
transfer case and linked up with the DSC driving control system. This allowed
it to provide an unrivalled platform for power distribution that could be
adjusted as necessary at all times. For the first time, the driving situation could
be analysed not only on the basis of wheel speed, but also using data
supplied by the DSC system on steering angle, accelerator position and
lateral acceleration, including the driving status deduced from these
parameters. This laid the foundations for xDrive to become the world’s only
intelligent all-wheel-drive system, a status it retains to this day. In contrast to
conventional all-wheel-drive systems, which merely react to wheels that are
already spinning, xDrive can identify any tendency to oversteer or understeer
at an early stage and counteract it pre-emptively by adjusting the distribution
of drive.
Over the years that followed it was not only the two X models that benefited
from the exceptionally rapid and precisely calculated distribution of power,
but also the BMW 5 Series Saloon and Touring models and the BMW 3
Series. In 2005, all-wheel-drive variants were introduced both for the fifth
generation of the BMW 3 Series and for the fifth-generation BMW 5 Series
launched a short time earlier.
More than 600,000 units of the first-generation BMW X3 were sold worldwide
before it handed over to the new model in 2010. A little earlier the BMW X5,
the second generation of which had been in production since 2006, had
passed the million-unit mark.
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Assured traction, superior dynamics: BMW xDrive with new
calibration and Dynamic Performance Control.
The extraordinary potential of both the BMW X model concept and xDrive
technology has since spawned another wave of innovations. For example,
the BMW X6 – still the world’s only Sports Activity Coupé – was launched in
2008, and the BMW ActiveHybrid X6 is also fitted with xDrive. Since 2009
the BMW X1 has been the only vehicle of its kind in the premium compact
As in the new BMW X3, xDrive can also be combined with Performance
Control in the BMW X1 to make its handling even more agile. Carefully
calculated brake impulses applied to the inside rear wheel around a corner
combine with a simultaneous increase in engine power to ensure that the
vehicle turns in extremely quickly and precisely. The BMW X6 is fitted as
standard with Dynamic Performance Control, giving it even greater scope
for adjusting the distribution of power. This system teams up with xDrive to
provide the most captivating expression yet of BMW’s hallmark driving
pleasure through corners. Dynamic Performance Control uses variable
distribution of drive between the inside and outside rear wheel to enable
exceptional agility and stability around corners, even under sudden load
changes or in overrun.
The interplay of xDrive and Dynamic Performance Control can be experienced
at its most intense in the BMW X5 M and BMW X6 M. The first high-
performance sports cars with all-wheel drive to come out of BMW M GmbH
are powered by an eight-cylinder engine with M TwinPower Turbo
technology developing 408 kW/555 hp.
Alongside the impressive progress of the BMW X models, the range of all-
wheel-drive variants of other model series has also been consistently
expanding. xDrive is now available not only for the Saloon and Touring
versions of the BMW 3 Series but also for the Coupé; a total of 15 model
variants from the 3 Series range now have all-wheel drive. Four engine
variants of the BMW 5 Series Gran Turismo are also available with xDrive.
With its new set-up designed to enhance agility and precision through
corners, xDrive offers a better platform than ever when it comes to providing
an intensive driving experience and an ideal combination of dynamic capability
and comfort. It was therefore no surprise to see all-wheel drive also being
welcomed into the BMW 7 Series range. Customers can choose from three
all-wheel-drive variants of the luxury Saloon – the BMW 750i xDrive,
BMW 750Li xDrive and BMW 740d xDrive.
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