Munich. The next generation of the BMW 3 Series
Limousine is just completing the crucial stages on the way to serial
production maturity. There was only one possible setting when it came
to driving dynamics testing and set-up runs: the legendary
Nordschleife at Nürburgring. Test runs at the “Green Hell”
traditionally serve as an endurance test for the drive and suspension
technology of newly developed BMW models. A particularly extensive
testing programme was developed for the camouflaged prototypes of the
new BMW 3 Sedan. After all, the comprehensive renewal of the wheel
suspension, steering, damping/suspension and brakes provided the
developers with a broad range of opportunities to optimise ride
comfort and dynamic performance, enabling the ultimate sports sedan
for the mid-range premium segment to mature lap by lap.
The underlying concept of the four-door model shows just how much the
development process for the new BMW 3 Series Sedan is geared towards
enhanced sporty flair. The centre of gravity is some 10 millimetres
lower than in the predecessor model, axle load distribution is
balanced at a harmonious 50 : 50 and the total weight adjusted for
fittings is as much as 55 kilograms less. Meanwhile the rigidity
levels of the body structure and suspension attachment – so crucial to
the steering set-up and ride acoustics – have been significantly
enhanced. The car’s agility and steering precision benefit from much
expanded track widths, while increased wheel camber levels offer
additional potential for maximum transverse dynamics.
In terms of the engine portfolio, one particularly striking feature
is a thoroughly revised 4-cylinder petrol engine. It is the most
powerful 4-cylinder engine ever to be fitted in a BMW series
production model. Yet its fuel consumption figures are still some 5
per cent below those of the predecessor engine: one contributing
factor here is the further developed 8-speed Steptronic transmission.
What is more, a particulate filter optimises the emissions response of
the new engine, enabling it to meet the Euro 6d-TEMP exhaust standard.
Not only is the body lighter and more rigid in design than that of
the predecessor model, the same is also true of the front and rear
axle in the new BMW 3 Series Sedan. The result is a specific
orientation of the axle kinematics and elastokinematics towards
supreme yet sporty drive properties. The key feature in terms of
suspension development in the new BMW 3 Series Sedan is its innovative
damping system. The first ever lift-related dampers ever to be fitted
in a BMW model function continuously and progressively in relation to
the respective spring travel. As such, the vibrations that occur when
compensating for bumps on the road and during dynamic cornering can be
neutralised especially gently and precisely – the perfect basis for
striking a unique balance between sporty flair and ride comfort, which
is very much a defining characteristic of the new BMW 3 Series Sedan.
Long known for its diversity, the track layout of the Nürburgring
Nordschleife quickly transpired as the perfect setting for selective
refinement of the interaction between the new damping technology and
the other suspension components. “We’re using the lift-related
dampers as an active set-up element so as to create supreme driving
properties in all conditions,” explains Peter Langen, Head of
Driving Dynamics. “With short spring travel, a sensitive damping
response ensures comfortable vibration compensation. When the car
passes over large bumps, the body movements are controlled by
increased damping forces.”
The lift-related dampers are a standard feature of the suspension
technology in the new BMW 3 Series Sedan. In a specific set-up they
also form part of the M sports suspension, which additionally includes
a lowering of 10 millimetres, 18-inch light alloy wheels and mixed
tyres. This provides a boost to driving dynamics – something that can
be experienced more intensely than ever before. The increased damping
forces can be felt on the Nordschleife in particular: in the M sports
suspension these are some 20 per cent higher than in the standard
suspension. “This means the difference from the standard
suspension is much more perceptible than before,” says Peter
Langen. “We’ve also made the M sports suspension much sportier,
with more rigid bearings and stabilisers, harder springs and
additional body struts.”
In order to further reinforce the car’s dynamic characteristics, the
new M sports suspension is offered solely in combination with the
Variable Sports Steering. In addition to the speed-related steering
assistance Servotronic, this also provides a variable steering ratio.
Variable Sports Steering has also been specially reconfigured for the
new BMW 3 Series Sedan. It already responds with much greater
precision to slight steering movements, without seeming nervous in
central position. The harmonious set-up of the steering system can be
felt on long bends as well as when changing direction several times in
rapid succession. A linear build-up of steering forces and optimised
feedback increase precision when cornering in dynamic style.
The M sports differential is able to perfectly demonstrate its
qualities on both the Nordschleife and the Grand Prix circuit. The
electronically controlled locking function in the rear axle
differential of the new BMW 3 Series Sedan is linked to Dynamic
Stability Control DSC, ensuring needs-oriented limitation of rotation
speed compensation between the rear wheels on the inside and on the
outside of the bend. Depending on the situation on the road therefore,
it is possible to pre-emptively influence both understeering and
oversteering without brake intervention. The active differential lock
distributes drive torque selectively between the rear wheels. In this
way, it prevents slip on a wheel with reduced surface grip while
ensuring that the engine power can be used unrestrictedly to generate
sporty driving pleasure. “Unlike conventional mechanical locks,
the regulated M sports differential can optimise so much more than
just traction,” says Peter Langen. “In addition to cornering
dynamics, there is a particularly tangible increase in drive stability
in the event of load changes, for example. This allows the new BMW 3
Series Sedan to be driven remarkably confidently and effortlessly even
when travelling in dynamic style.” For sporty driving, the active
differential lock provides much higher levels of transverse
acceleration as well as a perceptible boost in dynamic performance
when accelerating out of bends. It also supports optimised stability,
precision and cornering predictability in the new BMW 3 Series Sedan –
without brake intervention.