25_years_of_BMW_all-wheel-drive_detailed.pdf

25 years of BMW all-wheel-drive

expertise.

Contents.

BMW

Media

Information

10/2010

Page 1

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

expertise.

(Short version)

BMW

Media

Information

10/2010

Page 2

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.

BMW

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Information

10/2010

Page 3

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.

BMW

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10/2010

Page 4

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.

BMW

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10/2010

Page 5

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

segment.

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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