compact
Traction, comfort and safety:
Mercedes-Benz SUVs and off-road models
Mercedes-Benz has a leading position in the SUV segment. No premium manufacturer offers a compara-
ble choice of off-road-capable vehicles: from the new GLK-Class compact SUV via the the luxury M and
GL-Class off-roaders up to the G-Class - the unique combination of luxury and rustic off-road vehicle.
Permanent all-wheel drive and converter automatics – the ideal combination for driving dynamics and
assertiveness – are standard in all Mercedes-Benz off-roaders. Comfort, dynamics and good off-road ca-
pability are however not the only strengths of the Mercedes-Benz all-wheel drives. Customers who need
vehicles with powerful traction appreciate the combination of superior traction and uncompromising
safety.
ADVANTAGEScompact presents the three different all-wheel drive systems from Mercedes-Benz and
takes a look at the key competitors. Mercedes-Benz sets standards in the compact SUV class with its
new GLK-Class, not least due to its own, independent all-wheel drive in this segment.
The GLK-Class – new standards in the compact SUV segment
Compared with all the competitors, the GLK-Class sets standards in driving dynamics, ride comfort and
off-roadcapability thanks to 4MATIC, a purely Mercedes-Benz development. The lengthways installa-
tion of engine and gearbox and other innovative design details provide advantages over the compact
SUVs from the competition:
> Permanent all-wheel drive – always active and without the re-
action time of systems that have to be engaged.
> Asymmetric torque distribution of 45% front/55% rear sup-
ports agility, stability and longitudinal traction at all times.
Product information > Twin-disc clutch with 50 Nm locking torque between front and
for the Mercedes Benz rear axles improves the traction on and off the road.
sales organisation > The driving behaviour is always very predictable.
No. 14 - 2008 > Distributor gearing, epicyclic differential and multi-disc clutch
The GLK-Class offers an impressive overall are integrated into the gearbox: no sacrifices in foot space of
package of design, agility and comfort. The the front passenger.
4MATIC has a decisive share in this
> The only vehicle in the segment with 7-speed converter auto-
matic (7G-TRONIC) and all-wheel drive.
> Converter automatic as standard: up to 3-fold increase in
torque brings benefits when pulling away with a trailer and
when off-road. Clutch wear or damage as in manual gearboxes
is not possible.
> Low consumption due especially to high efficiency and low
weight of the drive train.
compact Audi Q5: the only competitor to the GLK with permanent all-wheel
drive
The only compact SUV with permanent all-wheel drive is the Audi Q5 that is available in Germany
from November 2008. Like the GLK-Class, it also has the length-
ways built-in drive unit and asymmetric torque distribution
(here: 40% front/60% rear). The drive is already well known from
the Audi A4. The difference to the 4MATIC is however the torque
distribution using a self-regulating Torsen differential:
> Torque distributions of 15% front/85 % rear and
65% front/35 % rear are possible.
A Torsen differential distributes the torque be- > The torque distribution without including driving dynamic
tween the front and rear in the new Audi Q5
parameters can lead to unharmonious over/understeer.
BMW X3: an all-wheel drive for high agility.
The BMW X3 certainly also has a lengthways built-in drive train, but does without a permanent all-
wheel drive: the drive to the front wheels is only engaged via an electrically actuated multi-disc clutch
with a continuous adjustment from 0% front/100% rear to 50% front/50% rear as required. The develop-
ers had the high driving dynamics especially in mind. This is matched by the very stiff springing that
already limits the traction over light terrain and so necessitates braking action from the all-wheel drive
system.
> The xDrive can certainly simulate a central differential lock for
a short period of time but a mid-differential brake is lacking.
> The transition from rear to all-wheel drive causes unaccus-
tomed under/oversteer. When manoeuvring, the X3 only uses
rear-wheel drive in order to avoid stressing the transmission.
> The friction clutch is subject to a certain wear due to its de-
sign - in contrast to the differential in the GLK-Class.
In the BMW X3, the drive is subordinate to the
driving dynamics
Haldex everywhere: Land Rover Freelander, Volvo XC60 and VW Tiguan
Land Rover Freelander, Volvo XC60 and Volkswagen Tiguan require an (uneconomical) torque redirec-
tion to the rear axle because of their transversely installed engines. This is why they nearly always
drive using the front wheels. An active, electronically controlled multi-disc clutch from the Swedish
supplier, Haldex, connects the rear axle to the front drive train only if required. "Fast computers, such as
those in the Tiguan, can certainly simulate a ... four-wheel drive, but cannot react quickly enough when un-
der pressure" (Off Road/D, 02/08).
Product information
for the Mercedes Benz > Only 10 % of the torque gets to the rear. The multi-disc clutch
sales organisation responds to slip on the front axle and then involves the rear
No. 14 - 2008 axle up to 50 % in the propulsion. When manoeuvring, only
the front wheels are driven in order to avoid stressing the
transmission.
> As the Haldex clutch normally distributes 90 % of the torque
to the front, the typical disadvantages of front-wheel drive are
The system from the Swedish supplier, Haldex, retained: steering effects and the tendency to understeer.
is making advances: Land Rover Freelander
... Volvo XC60 share the same all-wheel drive ... while VW uses a similar system - also with
technology with the Haldex clutch ... clutch supplied by Haldex
2
compact The G-Class: permanent all-wheel drive, three locks plus 4ETS
The G-Class is rightly called an off-road legend. Other than in the few other off-roaders that today still
have a ladder frame chassis and two rigid axles, the G-Class has been fitted with a perfect all-wheel
drive system supplemented by electronic control systems that make driving even easier to operate and
more comfortable: Today the G-Class is worldwide the only off-road vehicle with three genuine differen-
tial locks, a transfer box that can be engaged at up to 40 km/h and an additional traction system (4ETS).
There is also ESP and BAS.
> Converter automatic as standard: up to 3-fold increase in
torque brings benefits when pulling a trailer and when off-
road. Clutch wear or damage as in manual gearboxes is not
possible.
> Permanent all-wheel drive with variable torque distribution
50% front/50% rear.
> 4ETS transfers the torque to the wheels that have traction:
perfect for easier off-road areas.
The G-Class is a classical off-roader and is the > The driver can manually lock all three differentials in suc-
only vehicle to provide three locks cession for extreme stretches. The efficiency is unsurpassed,
especially with experienced drivers.
"The three differential locks had the power to master all the un-
metalled roads in the world" (Automobil Revue/A, 10/07)
Comfortable, safe – and very off-road capable: M and GL-Classes
Other than most of the competitors in the segment, the M and GL-Classes provide a high degree of
comfort and safety on the road and are also very capable off-road. This is thanks to their converter auto-
matics that, with up to three times the torque, provide benefits in trailer and off-road operation and to
the permanent all-wheel drive (torque distribution of 50% front/50% rear). Also making a contribution
are the Offroad Pro Technology package "OPTP" with reduction box (2.93:1, can be engaged at up to 40
km/h), AIRMATIC and differential brakes with mid and rear lock functions. As with the G-Class, 4ETS
initially increases the torque to those wheels with good surface
adhesion. For higher loads, the automatic differential brakes take
effect and these increase the drive efficiency. Further benefits of
automatic differential brakes:
> Can be engaged at any time when under way and in bends.
> Immediate response - lock immediately.
> Prevent damage to drive train and lock.
M and GL-Classes are the off-road benchmarks
> Self-releasing when not used, so averting accident risk on the
in their respective segments road.
Product information
for the Mercedes Benz
Audi Q7: the focus is on agility
sales organisation
No. 14 - 2008 The drive train of the Q7 is characterised by permanent all-wheel drive, 40% front/60% rear torque dis-
tribution designed for driving dynamics, and self-locking Torsen central differential. Reduction box and
differential locks are however not available. The only traction aid available is brake intervention. The
all-wheel system designed in this way certainly increases the agility of the Q7 but hardly its off-road-
capability:
> With no reduction available, the drive is quickly over-taxed
off road by the great
weight of the Q7.
> Braking action as the only locking substitute is not sufficient
in view of the low suspension mobility.
> With no transfer case, the increase in torque is missing that
is so important off-road or when towing and also the ability to
drive slowly off road, so lessening damage to material.
The Q7 is a large estate that merely flirts with
the subject of "off-road"
3
compact BMW X5 xDrive: all-wheel drive only when required
The X5 provides rear-wheel drive with all-wheel drive controlled via an electrically actuated multi-disc
clutch that can be continuously adjusted from 0% front/100% rear to 50% front/50% rear as required.
This system, which has been designed for driving dynamics, offers neither off-road reduction nor differ-
ential locks and a traction control only by means of brake intervention. In principle it is the same as in
the smaller BMW X3, but in a heavier vehicle with greater trailer load. The hard springing also means
that the traction is lost much earlier. The all-wheel drive is then over-taxed even with the typical SUV
requirements.
> The xDrive can simulate a central differential lock for a short
period of time but there are no axle differential locks or
brakes.
> With no transfer case, the increase in torque so important off-
road or when towing and the ability to drive slowly off road so
lessening damage to material, has to be dispensed with.
"It makes no sense to leave the asphalt road as the orientation is
Driving dynamics rather than the art of climb- consistently towards on-road driving" (Off Road/D, No. 03/07).
ing: a typical BMW
Land Rover Range Rover: all-wheel drive with programme preselection
The distinguished Briton provides permanent all-wheel drive, an electronically controlled multi-disc
brake with lock function in the central differential and an off-road reduction gear of 2.93:1 (the distribu-
tor gearbox from Magna Steyr Powertrain is the same as that in the M and GL-Classes). A traction con-
trol is standard, an automatic multi-disc brake with lock function is available for the rear differential as
an optional extra.
> "Terrain Response" (TRS), an automatic control of the all-
wheel drive system for different surfaces, sets braking action
and locks and controls the shift speeds.
> An off-road reduction of 2.93:1 gives very good crawling speed
qualities and high torque at the drive wheels.
> The Range Rover is certainly on a par with the M and GL-
Classes off-road, but offers little agility on-road.
The Range Rover is very capable off road, but
with reductions in agility
Porsche Cayenne: flexible with off-road technology
Product information The Porsche Cayenne is fitted with permanent all-wheel drive and off-road reduction. The torque dis-
for the Mercedes Benz tribution with 38% front /62% rear is designed for driving dynamics. There is in addition an automatic
sales organisation multi-disc lock in the central differential. The reduction is rather short at 2.7:1 and can be engaged at
No. 14 - 2008 up to 15 km/h. An Off-road package (optional extra) includes a multi-disc lock at the rear and decoupla-
ble stabilisers. The latter increase the axle mobility by 60 mm and so improve the traction. The sports-
positioned Cayenne GTS launched at the beginning of 2008 only exploits the advantage of all-wheel
drive and dispenses with all off-road features.
> The Porsche Cayenne needs the complete, complicated off-
road technology (optional extra) to compensate for the traction
drawbacks caused by the driving dynamically-stiff suspension
design.
> Transfer case and off-road package manage to walk the in-
teresting tightrope between agility and climbing ability – but
only after changing the tyres.
Technically related to the VW Touareg, the Cay-
enne places the emphasis on driving dynamics
4
compact Toyota Land Cruiser: new edition with two Torsen differentials
The Land Cruiser series, that has been running since 1951, has permanent all-wheel drive in its latest
generation - also a manually lockable Torsen limited-slip differential (LSD) with a drive torque distribu-
tion ranging from 40% front/60% rear to 30% front/70% rear. It also has an off-road reduction (2.618:1).
There is a second Torsen differential in the rear axle. The terrain-dependent speed control system
("Crawl Control") is only available in the petrol-engined version.
> The Land Cruiser has high axle mobility and good traction
thanks to the rigid rear axle.
> The good articulation has been further improved by an
active control of stabilisers and springs (optional extra).
> The use of traction aids and locks is only necessary relatively
late.
> The rear differential only reacts automatically and cannot be
manually locked.
Toyota completely backs Torsen differentials;
the Land Cruiser even has two
Volkswagen Touareg: a well-balanced compromise
Volkswagen has also decided on permanent all-wheel drive; the standard torque distribution here is
50% front/50% rear. An automatic multi-disc brake with lock function in the central differential and an
off-road reduction of 2.7:1 are standard. This can, however, only be engaged at up to 15 km/h. There is
an option of an automatic rear multi-disc brake with locking function. The decouplable stabilisers also
cost extra. They increase axle mobility and thus improve the traction.
> The comfortable Volkswagens achieve usable performance
with the off-road options. They get close to the M and GL-
Classes without actually reaching that level.
> As a comparison, three off-road figures in VW vs. Mercedes-
Benz:
Reduction: 2.7:1 vs. 2,93:1
Reduction engageable up to: 15 vs. 40 km/h
The VW Touareg provides comfort but is some- Wading depth: 580 vs. 600 mm
what less off-road capable than the M-Class
"the Touareg has no chance against the successful Mercedes ML
all-wheel drive" (Auto Bild/D, No. 06/07).
Conclusions: Mercedes-Benz SUVs and off-roaders offer unique advantages
Product information
for the Mercedes Benz Mercedes-Benz demonstrates the highest degree of consistency with its all-wheel drive designs in the
sales organisation area of SUVs and off-roaders and fits permanent all-wheel drive to the entire range. This type of drive
No. 14 - 2008 offers undoubtedly the greatest benefit to the customer both on-road and in difficult terrain. Not even
Land Rover, the declared off-road specialist, offers its customers so much competence today.
But it is not only the all-wheel drive that counts. The Mercedes-
Benz SUVs and off-roaders, as in the entire Mercedes-Benz
range, impress with their innovative details, high quality, com-
prehensive safety and exclusive equipment.
Mercedes-Benz stands out with the best long-term prospects in
this above-average growth market of off-road capable, all-wheel
drive vehicles.
The Mercedes-Benz SUV range provides the
right vehicle for every use
