BMW 3 Series suspension technology:The milestones (2): Thanks to sporty, agile and safe handling, the fifth generation of BMW's bestseller sets a further benchmark in terms of driving fun.

Munich. More driving fun in the medium class car segment: It was under this
premise that, in 1975, BMW presented an entirely new concept. With the BMW 3
Series brand-typical virtues such as dynamics and agility became factors of
success in this segment for the very first time. The sporty saloon's unique
handling characteristics convinced right from the word go.

The unmistakable character of the BMW 3 Series was the result of a consistently
implemented basic concept: high-performance engines were complemented by power
transfer to the rear wheels, even load distribution and an advanced chassis
construction. As early as1975, the technically sophisticated wheel suspension,
remarkably precise, torque steer-free steering and powerful brakes guaranteed
the driver of a BMW 3 Series car exceptionally sporty and safe vehicle handling
in any situation. A standard still applicable to this very day. Even if every
single component of the suspension technology has been subject to a remarkable
development process over the past 33 years, the basic concept of driving
pleasure does indeed remain in existence to this very day. Thanks to the most
modern suspension system in its segment, the BMW 3 Series today still sets the
benchmark in sportiness and agile handling.

1975: Premiere of the BMW 3 Series - performance and suspension at luxury class
level.
The new series was launched in 1975, comprising the BMW 316, the BMW 318, the
BMW 320 and the BMW 320i and four engine variants. With its 98 bhp
four-cylinder engine even the BMW 318 almost entered the domain of triple-digit
performance values then predominantly reserved only to luxury class vehicles.
However, in terms of suspension technology, all versions of the BMW 3 Series
already surpassed normal standards typical of their respective segment. They
were also a match for pure sports cars. The sports suspension featured by the
first model generation had wheels individually suspended on transverse arms
with spring struts at the front and likewise, at the rear, independent wheel
suspension with semi-trailing arms and spring struts. This combination
facilitated the harmonisation of an above-average driving dynamics potential
with a high degree of comfort.

The transverse arms on the front axle were guided by stabilisers according to
the McPherson principle, the new front axle construction offering ideal
preconditions for high steering precision. Also, with the BMW 3 Series an
entirely new design feature made its debut at BMW - the flexibly mounted
rack-and-pinion steering. The steering column now comprised the following
components: steering shaft, cardan joint and flexible discs.

Better performance, enhanced technology: disc brakes all round and optional
servo steering for the six-cylinder versions.
The BMW 3 Series of the first generation came with 13-inch steel rims as
standard. Alloys of the same size were available as an option. Thanks to disc
brakes on the front wheels and drum brakes at the rear, excellent deceleration
values were achieved from the word go. However, with the introduction to the
BMW 3 Series of the exceptionally powerful six-cylinder power units, it became
necessary to employ brakes that were even more effective. Consequently, the BMW
323i, the series' top-of-the-range model launched in 1977 and delivering 105
kW/143 bhp, was also equipped with disc brakes on the rear wheels. Moreover, as
in the case of the BMW 320/6, the steering could be optionally fitted with
hydraulic power steering technology.

1982: The second generation - even more agile, even safer.
1982 saw the arrival of the second generation of the BMW 3 Series, a worthy
successor to the trendsetter and bestseller. The new model reflected
advancement and variety in every aspect - new design, optimised aerodynamics,
increased space and comfort, higher power output, additional body and engine
variants. For example, during its lifespan a four-door version, the first BMW 3
Series Touring, the Convertible and the BMW M3 sports car were introduced.
Furthermore, diesel engines and four-wheel drive were added to the BMW 3 Series
portfolio. This strategy was most successful. With more than 2.3 million units
sold, its predecessor's sales figures were topped by a million vehicles.

In terms of agility, driving safety and handling precision the second
generation of the BMW 3 Series also outshone all competitors in its segment.
Engineers had modified the front axle of the new BMW 3 Series in order to
increase active safety even further, without affecting the typical handling
characteristics. At the front, the new 3 Series featured a single-joint spring
strut suspension with sickle-shaped transverse control arms and a reduced
rolling radius to minimise the negative forces that affect steering.

The rear axle now incorporated semi-trailing arms with separate dampers and
springs. The newly designed barrel springs with progressive spring
characteristics provided enhanced comfort, particularly on slightly uneven road
surfaces, and thanks to their compact design they also facilitated an increase
in boot capacity. The linkage of the rear semi-trailing arms now had a sweep of
only 15 degrees instead of 20.

Furthermore, the track, now widened by 35 millimetres, the low weight and
reduced aerodynamic resistance had a positive effect on the driving
characteristics of the new BMW 3 Series. At the time of its launch, there was a
choice of the two four-cylinder models BMW 316 (66 kW/90 bhp) and BMW 318i (77
kW/105 bhp) as well as the two six-cylinder versions BMW 320i (92 kW/125 bhp)
and BMW 323i (102 kW/139 bhp). A sports suspension was optionally available
from factory for all four versions. Also, alloy wheels were on offer as an
alternative to the standard 14-inch steel rims. The wheels, which were larger
compared to those featured on the predecessor model, offered sufficient room
for larger dimensioned brakes. New floating-calliper brakes replaced the
previously employed fixed-calliper design and a larger brake power assist unit
was added. The BMW 323i was once again fitted with disc brakes all round. The
front disc brakes were - as on the BMW 320i - ventilated.

Improved stability thanks to ABS and four-wheel drive.
For the first time, an optional electronic anti-lock brake system (ABS) was
available for the six-cylinder versions. Initially, BMW had employed this
innovative safety feature on the BMW 7 Series, but only a short while later the
premium technology was utilised for the high-output versions BMW 323i and BMW
320i. Sensors for wheel speed, a control unit and a hydraulic unit
automatically controlled wheel slip and wheel acceleration in such a way as to
prevent the wheels from locking in hazardous situations. This also ensured that
both stability and steerability were maintained when the brakes were applied,
even on slippery surfaces and in bends. From 1992, this feature was standard on
all BMW 3 Series models.

The modified rack-and-pinion steering provided better tractability and
increased precision on uneven road surfaces. The power steering technology
already employed on the six-cylinder versions of the predecessors was now
available for all models as an option.

In the year 1985, the top-of-the-range model was toppled from its leading
position by the 126 kW/171 bhp six-cylinder model BMW 325i, which then already
featured ABS as standard. At the same time the BMW 325iX, the version with the
best traction and four-wheel drive, was launched. Right from the start, BMW
engineers were not satisfied with simply an on-demand front-wheel drive. In
fact the transfer gearbox with automatic viscous locks permitted ABS-compatible
and permanent four-wheel drive. This resulted in optimised traction in all road
conditions and the highest degree of stability in every motoring situation. In
normal operation 63 percent of power was transferred to the rear axle and 37
percent to the front. So power transmission had very little effect on the
steering. Hence the BMW 325iX convinced through exceptionally harmonious
driving behaviour.

Inspired by motor sports, geared to performance: the BMW M3.
Finally, at the 1985 International Motor Show in Frankfurt, the spotlight
focused on a further newcomer that set the pulse of many a motor sports
enthusiast racing - the first BMW M3. Developed on the basis of the two-door
BMW 3 Series Saloon and powered by a 147 kW/200 bhp four-cylinder engine, an
uncompromising sports car had entered the scene. The first chapter of an
unrivalled success story, that has lasted to this day, had been written.

Not only was the BMW M3's power unit inspired by motor sports, but also its
suspension technology. For instance, axle kinematics, springs and dampers were
extensively modified and adapted to racing standards and to the high engine
performance. The brake system with ABS as standard comprised internally
ventilated brake discs at the front and an engine-driven high pressure pump.
This servo pump simultaneously supplied power to the steering, so that both
systems operated independently from negative engine pressure.

In the model year 1987, the M3 was also the first BMW to offer electrically
adjustable dampers. The driver could choose between "Sport", "Normal" and
"Comfort" using a rotary switch located next to the handbrake lever. Control
lamps on the dashboard indicated which setting had been selected.

1990: The third generation of the BMW 3 Series - more agility, enhanced
precision and electronic slip control.
The third BMW 3 Series generation made its first appearance in October 1990,
featuring boldly elongated contours and thoroughly revised technology. At the
time of its launch a choice of two four-cylinder and two six-cylinder versions
was made available. The BMW 316i served as an entry version with an output of
74 kW/100 bhp, the BMW 318i delivering 83 kW/113 bhp, and the two straight
six-cylinder versions featured in the BMW 320i and the 325i mustered 110 kW/150
bhp and 141 kW/192 bhp respectively. The long 2,700-millimetre wheelbase and
the elongated body made a promise of sheer driving pleasure and the chassis
also came well up to expectations.

The third generation of the BMW 3 Series ran on a single-joint spring strut
axle with transverse stabilisers at the front, and now featured a rear axle
with a central control arm and two transverse control arms arranged on top of
each other for optimised stability particularly in bends, harmonious running
characteristics and enhanced suspension comfort.

Both front and the rear axles were fitted with double-pipe gas pressure
dampers. For the first time engineers had designed the rear track to be wider
than at the front. This structural design remained in use for the model
generations that followed.

Power assisted steering for the even further developed rack-and-pinion steering
was now a standard feature on the BMW 318i. For the first time the driver was
not only able to adjust the seats individually, but also adjust the steering
column axially in order to find his or her ideal position behind the wheel.

An M technology sports suspension lowered by15 millimetres was available as an
option. The wheels, either steel or light-alloy, depending on the model, had
increased in size to 15 inches. The effectiveness of the brakes was also
increased even further. The four-cylinder models featured disc brakes at the
front combined with drum brakes on the rear wheels, the six-cylinder versions
being fitted with disc brakes all round, including internally ventilated discs
at the front.

The top-of-the-range model, the BMW 325i, came with ABS as standard, further
versions offering this state-of-the-art system initially as an option and, as
from 1992, as a standard feature. In addition, Automatic Stability Control
(ASC) was included in the range of optional equipment. Irrespective of the
driver's accelerator pedal input, the anti-slip control system permitted only a
limited amount of engine power to be conveyed to the drive wheels in each
respective driving situation to prevent the wheels from spinning. From 1997,
the enhanced form of this technology termed ASC+T, with additional braking
intervention for stability, was available for all BMW 3 Series models.

The new edition of the BMW M3, which was based on the BMW 3 Series Coupe and
launched in 1992, also impressed with further enhanced dynamics resulting from
the newly developed 3-litre straight six-cylinder power unit with an output of
210 kW/286 bhp as well as an entirely re-engineered suspension. The
single-joint spring strut front axle was complemented with reinforced spring
seats and axle stubs. And the new central-arm rear axle was, inter alia,
adapted to the high engine output through the addition of modified longitudinal
arms. Furthermore, dampers and stabilisers were now significantly firmer. These
modifications were also reflected in the body height: The BMW M3 was precisely
31 millimetres lower than a BMW 3 Series Coupe. The so-called compound brakes
at the front were a further highlight. Due to the compound construction
comprising an aluminium brake-disc chamber and a grey cast iron friction ring,
the disc was able to expand without distorting as the brakes were applied.
Thanks to its dynamic and superior handling characteristics, the new BMW M3 set
standards internationally in terms of sportive driving pleasure. Hence it was,
for example, voted "Best Handling Car" by experts from the US car magazine "Car
and Driver".

1998: The fourth generation with a consistent lightweight construction and
innovative stability control systems.
BMW developed a newly conceived lightweight suspension and innovative stability
control systems for the fourth generation of the BMW 3 Series. With its basic
construction and its technical highlights, the suspension technology reached a
level previously only found on luxury class automobiles. The proportion of
aluminium used on the suspension was now around 60 kilograms, i.e. 20 percent
of the overall weight. Moreover, a further optimisation was achieved through
the selective use of high-strength steel on front and rear axle supports. The
overall construction was significantly lighter than that of the previous model
and facilitated a further increase in agility. In addition to the distinctively
increased body stiffness, the familiar even axle load distribution contributed
towards the harmonious, stable and constantly controllable handling
characteristics of the BMW 3 Series.

The fourth BMW 3 Series generation had a 25 mm longer wheelbase and a 60 mm
wider track than its predecessor. The elongated body contours distinctively
reflected the saloon's sporting character, driving dynamics even directly
benefiting from its further reduced aerodynamic resistance. With regard to
kinematics and elasto-kinematics, the central-arm rear axle with double-pipe
gas damper and stabiliser corresponded to the construction of the previous
model.

The use of high-strength steel for the rear axle improved vibrational
behaviour, and a double-elastic rear suspension with rubber mountings provided
additional comfort. In addition, the well-proven concept of a single-joint
spring strut suspension with transverse stabilisers at the front was developed
even further and complemented, inter alia, with a hydraulically damped
transverse arm mount.

With the exception of the BMW 328i, which featured 16-inch alloys as standard,
all variants of the fourth BMW 3 Series generation stood on 15-inch rims.
During the years that followed a variety of light-alloy rims in various sizes
up to 18 inches were available as an option. As in the case of the predecessor,
power assisted steering was again included in the list of standard features
and, for the first time, the steering column could not only be adjusted
axially, but also in height.

Premiere for groundbreaking stability control systems: CBC and DSC.
Once again, a significant advancement had been achieved with regard to brake
and stability control systems. All fourth-generation BMW 3 Series models were
fitted with disc brakes all round. Their degree of effectiveness was optimised
by ABS, which was now also a standard feature. BMW also introduced the
Cornering Brake Control system (CBC), a further development of ABS and a
technology that facilitated optimal utilisation of the rear axle braking force,
but without having an adverse effect on tracking stability. It is the also task
of the system used on current BMW models to counteract the vehicle's tendency
to drift inwards if the brakes are applied when driving round bends at high
speeds. CBC identifies the situation and ensures that the vehicle is stabilised
by means of a controlled build-up of braking force to each individual wheel.
This counteracts the tendency to oversteer.

Likewise, the anti-slip control system ASC + T was again included in the range
of standard features on all BMW 3 Series vehicles. Dynamic Stability Control
(DSC) was a brand new technology initially only available for the 328i as an
option. This innovative system was designed to rapidly and accurately identify
any possible adverse effects on the vehicle's stability by measuring the yaw
rate and lateral acceleration and to prevent oversteer or understeer
particularly in bends by means of appropriate intervention. In this way it
became possible to re-establish vehicle stability by means of targeted brake
intervention on individual wheels as well as through a reduction in engine
power. DSC has been a standard feature on all BMW 3 Series models since 2001.

As early as 2000 it was possible to equip both the 3 Series Saloon and the 3
Series Touring with the new version of BMW four-wheel drive technology.
Permanent power transmission to all four wheels was linked to the Dynamic
Stability Control system. In this manner it was possible to achieve a
traction-enhancing locking effect by means of brake intervention on each
individual wheel. The new all-wheel technology was offered in combination with
six-cylinder engines. There was a choice of the variants 330xi, BMW 325xi and
BMW 330xd.

New BMW M3 with variable M differential lock.
The optimisation of the suspension system featured on the new generation of BMW
M3s - again developed on the basis of the BMW 3 Series Coupe and presented in
2000 - also managed to keep pace with technical advancement in the field of
drive technology. The BMW M3's new straight-six cylinder engine now delivered
252 kW/343 bhp, and thanks to high engine speeds and a comparably short axle
transmission, it developed enormous power that had to be safely and
consistently converted into driving dynamics.

The high-performance sports car profited from the exceptionally stiff body
structure of the BMW 3 Series, its even axle load distribution and the
weight-optimised suspension construction. In addition to individual suspension
components, both the compound brake system and the effect of the Dynamic
Stability Control system (DSC) were adapted to match the outstanding
performance of the high-revving power unit.

Furthermore, the new version of the torque-sensitive differential lock system
already employed on previous models offered improved traction in the event of
the vehicle being driven in a demanding fashion. The variable M differential
lock responded exceedingly sensitively to the varying friction values on the
drive wheels. Depending on the driving situation, a variable locking value of
between 0 and 100 percent could be produced. This ensured consistent optimum
traction under all load requirements, irrespective of the road surface.

2005: The fifth generation - with the best suspension in its segment.
With the market launch of the fifth model generation 30 years after its success
story had begun, the BMW 3 Series celebrated a spectacular anniversary in 2005.
BMW engineers had been successful in again bringing the suspension technology a
noticeable step forward, virtually bringing it in line with the characteristics
of the drivetrain and car body. This resulted in better agility and more
driving fun for the customer.

Thanks to a convincing and harmonious concept, the BMW 3 Series was able to
further strengthen its profile within its segment. The new symbiosis of
powerful engines, dynamic and cultivated driving characteristics, the
distinctive styling with the typical BMW design language, a torsionally stiff,
generously dimensioned body and innovative equipment features was a huge
international success right from the word go. Just a year after the market
launch, the new BMW 3 Series was awarded the title "World Car of the Year" in
New York.

Current BMW 3 Series models boast the largest and most varied range of engines
ever made available for the series. There is a choice of five petrol and five
diesel engines, both for the Saloon and the Touring model. Four petrol and four
diesel engines are available for the BMW 3 Series Coupe, whilst the BMW 3
Series Convertible comes in four petrol and three diesel versions. Output
ranges from 105 kW/143 bhp for the BMW 318i to 225 kW/306 bhp for the BMW 335i.
All-wheel drive - known as BMW xDrive technology with electronically
controlled, variable power distribution between front and rear wheels for
enhancing stability, traction and driving dynamics - is available for the
Saloon, the Touring and, now for the first time, the Coupe.

Innovative axle designs.
The fifth BMW 3 Series generation also has a larger chassis than its
predecessor. The wheelbase has increased by 35 mm and track width by 29 mm.
Depending on the model version, equipment and loading condition, the load on
the rear axle is between 48 and 56 percent, this being practically the ideal
value for even weight distribution.

The design of the front axle has once again been derived from technology
developed for the luxury class. The constructional concept comprising an axle
with double-joint tension rod and spring struts corresponds to the principle
used for the BMW 5 Series. Tension rods, transverse control arms, swivel
bearings and front axle support are made entirely of aluminium, a lightweight
concept with which BMW has made a particularly consistent advancement. A high
degree of stiffness and weight optimisation are combined in a unique manner.
Both characteristics have a positive effect on the vehicle's agility.

The five-link rear axle featured by the BMW 3 Series has been completely
redesigned. The unique construction offers ideal preconditions for a
particularly dynamic behaviour. With five individual control arms for each
wheel, virtual kinematic points can to a large extent be freely determined. The
large supporting base for track and camber on the wheel carrier side, extremely
rigid control arms, the stiff rear axle support and the connection to the car
body via pushrods facilitate elasto-kinematics that provide across a broad
spring travel range precisely the wheel control necessary for superior vehicle
handling in any situation. Furthermore, due to small and effective lever arms,
the rear axle is hardly affected by negative influences and facilitates
outstanding rolling characteristics. In addition, a well-balanced coordination
of springs and dampers enhances the BMW 3 Series' agile character.

Depending on the model variant, the BMW 3 Series comes with 16-inch or 17-inch
wheels as standard. The tyres have emergency running properties - likewise a
standard feature and unique in this segment - that allow the journey to be
continued even in the event of a total pressure loss. A tyre defect indicator
notifies the driver as soon as the pressure loss in a tyre exceeds 30 percent.
Disc brakes all round and ABS with the CBC Cornering Brake Control system are
standard features.

All BMW 3 Series variants are fitted with internally ventilated discs at the
front, six-cylinder versions and the BMW 320d additionally at the rear. Apart
from the high degree of effectiveness, a weight-optimised construction was
taken into account when developing the brake system. The continuous brake
lining wear indicator, that also calculates the remaining mileage, also
enhances safety and comfort.

State-of-the-art vehicle stability control with new functions.
The Dynamic Stability Control feature for the fifth-generation BMW 3 Series now
has a significantly broader functional range. The stabilising effect achieved
by means of brake intervention on each individual wheel and a reduction of
engine power has been complemented by numerous other possibilities of enhancing
safety and comfort in demanding driving situations. These include Automatic
Stability Control (ASC), trailer stability control and Dynamic Brake Control
(DBC), which automatically maximises brake force on both axles should it detect
that the driver wishes to brake as hard as possible. Moreover, the special mode
Dynamic Traction Control (DTC) can be selected at the push of a button, a
feature that raises the response threshold of the DSC system. This facilitates
better starting off on snow or loose sand and renders possible particularly
sporty driving behaviour and high lateral acceleration levels in bends.

The DSC system featured in BMW 3 Series six-cylinder models also includes
additional functions. By means of a systematic increase in brake pressure, the
decrease in stopping power known as fading is prevented in the event of
exceptionally high brake temperatures. Regular dry braking optimises brake
performance in wet weather. With the brake readiness function moderate brake
pressure is built up as soon as the driver takes his foot off the accelerator
pedal. This guarantees spontaneous brake response. Furthermore, a hill-start
assistant facilitates easier hill starts by preventing the vehicle from rolling
backwards for a defined period of time.

Steering: Precise, efficient and more dynamic thanks to Active Steering.
Typical BMW characteristics such as driving pleasure, driving comfort and
driving safety owe their existence to a considerable extent to the targeted
precision of the steering and the accurate response given to the driver. With
the exception of the BMW 335i and the BMW 335d, which are equipped with
rack-and-pinion steering with hydraulic power steering technology, all BMW 3
Series variants feature electro-mechanical steering EPS (Electric Power
Steering), which also includes the speed-dependent Servotronic steering
assistance system.

EPS features a steering assistant which operates by means of an electrical
actuator that can be utilised when required. The steering assistance system is
only activated if it becomes necessary or if the driver wishes. During constant
travel straight ahead the electrical actuator has no output. Hence EPS, an
integral part of the BMW EfficientDynamics programme, is making a contribution
towards a further reduction in the BMW 3 Series' consumption and emission
levels.

Active Steering, which is optionally available for the BMW 3 Series, provides
enhanced precision and steering comfort. In addition to the steering assistance
system or Servotronic respectively, Active Steering varies the steering ratio
according to driving speed. At low speeds a larger steering angle is
effectuated than at higher speeds, but with the same amount of steering wheel
movement. Consequently, less effort is required when parking the vehicle, for
example. Within the medium speed range Active Steering enhances the BMW 3
Series' agile character. In contrast, at higher speeds it aids directional
stability. Additionally, Active Steering adopts a stabilising effect in
particularly demanding driving situations. In the event of braking manoeuvres
on uneven surfaces (µ-split braking), the directional stability is maintained
through targeted and restrained counter-steer.