PKW4461 163 series M-Class, 1997–2001

163 series M-Class, 1997–2001

In January 1996 Mercedes-Benz presented the "AAVision" concept for an all-wheel drive utility vehicle at the North American International Auto Show in Detroit. This prototype sport utility vehicle drew considerable attention and already incorporated design elements from the Mercedes-Benz "All-Activity Vehicle" (AAV) that was being intensively developed at the time.

The European première of the AAVision design study took place two months later at the Geneva International Motor Show. It was here that the newest member of the Mercedes-Benz passenger car family appeared for the first time with the M-Class designation that it would take to production.

One year after the world première of AAVision, the public got their first look at the technology behind the M-Class, again at the Detroit Auto Show. On display were the chassis, the drivetrain with intelligent all-wheel drive, and the newly developed 3.2-litre V6 engine.

The chassis was based on a separate closed box section frame comprising two offset longitudinal members welded to three cross members, ensuring maximum stability and torsional stiffness. Both the front and rear cross members incorporated integral deformation elements designed to absorb the energy of a low-speed collision and protect the longitudinal members from damage. Damping to reduce transmission of road noise and bumps in the road surface was provided by sub-frames for the front and rear suspension in combination with ten rubber bushings.

Not content with just these unique chassis features, the new M-Class model range was also distinguished from its contemporaries by offering independent suspension on both front and rear axles. This concept provided not only a high level of driving stability and handling safety, but also allowed for increased ground clearance.

Each wheel of the front axle was controlled by two wishbones, with the upper control arm and the shock absorber both attached directly to the frame. The front sub-frame carried the lower control arm and the steering gear. The suspension arrangement incorporated torsion bars supported by the centre cross member, in combination with an anti-roll bar on the lower wishbones. The rear wheel suspension had a similar design, except that a combination of coil springs and shock absorbers with progressive spring rate was used in place of torsion bars. As at the front, the rear axle upper control arms and spring/damper assemblies were also mounted directly to the chassis frame and the lower wishbones and anti-roll bar were similarly carried by an sub-frame.

Permanent all-wheel drive was at the heart of the M-Class drivetrain concept: torque was distributed at a ratio of 48:52 from the transfer case (with integral central differential) to the front and rear axles via a one or two-part drive shaft. Unlike traditional all-wheel-drive vehicles, the drive system in the M-Class did away with conventional differential locks. This was made possible by use of a variant of the Electronic Traction System (ETS) modified specially for all-wheel-drive use. With ETS, if one wheel began to slip due to contact with a slippery surface, then an automatic intervention would increase the brake pressure on that wheel until a predefined speed differential was achieved. This increased the torque supplied to the wheels that had good traction to deliver maximum possible grip. Introducing ETS to replace conventional differential locks improved the manoeuvrability of the vehicle both on- and off-road. There was no longer any impairment of steerability or cornering stability, even during difficult driving manoeuvres.

Steering and braking systems also met the highest safety standards. The M-Class was equipped with rack-and-pinion power steering and a dual-circuit braking system with disc brakes on front and rear wheels; the front discs were vented. Standard equipment included an anti-lock braking system (ABS) adapted for off-road use. This system prevented the wheels prevented from locking at speeds above 8 km/h regardless of the quality of the road surface. When low-range was engaged at a speed of less than 30 km/h, a special off-road algorithm was activated that reduced the stopping distance on loose surfaces.

On 21 May 1997, just over four months after the innovative chassis and drive concept was presented in Detroit, the new sports utility vehicle finally celebrated its première. The venue was Tuscaloosa in the US state of Alabama, where the Board of Management assembled with more than 5000 guests, including the Governor of Alabama, to inaugurate the M-Class production plant that same day.

Tuscaloosa was chosen as the preferred site on 30 September 1993 following a comprehensive selection process, with the ground-breaking ceremony taking place on 4 May 1994. A mere three months later, Mercedes-Benz U.S. International, Inc. (MBUSI), founded specifically to oversee development, planning and production of the M-Class, began a wide-ranging recruitment campaign to find qualified staff for the new factory. In spring 1995, the first employees were being hired and prepared for their new roles with intensive training at Mercedes-Benz sites in Germany, including Sindelfingen. Production of vehicles finally started in February 1997.

MBUSI worked together with 65 system suppliers to produce the first generation of the M-Class. These suppliers delivered complete, pre-assembled modules with the required specifications directly to the assembly line on a just-in-time, just-in-sequence basis. This meant that the new factory required a vertical integration level of only 20 percent.

The M-Class, internally designated as W 163, was a testament to the company’s globalisation ambitions. Furthermore, alongside the CLK and A-Class, it was one of three new model series in 1997, and represented a significant milestone in the strategic product initiative. Press and public alike were overwhelmingly positive in their reception of the new SUV and production capacity was barely able to meet demand. Such success was attributable to the competitive price, high standard of safety, appealing design, and, of course, the all-round versatility of the concept. The model series 163 M-Class combined the comfort and handling safety of a Mercedes-Benz car with the robustness and off-road capabilities of a cross-country vehicle. On top of this, it also offered the space and variability of a people carrier.

The rear seat backrest was split into three folding sections, while the seat cushion was divided into one-third and two-third sections that could also be folded forward, giving numerous options for reconfiguration of the interior. A second row of single rear seats to accommodate two additional passengers was available as an optional extra; these could be easily removed or folded up to the sides when not in use.

In addition, the M-Class came equipped with numerous technical innovations that further improved safety, comfort and economy. These included the ELCODE drive authorisation system which was operated by an electronic door and ignition key and perfectly combined theft protection with convenience. The system was one component in a high-performance data network that provided fast, reliable communication for the control units in the engine bay and interior. Mercedes-Benz was the first manufacturer in the world to connect local subnets via a data interface to create a comprehensive digital network.

Another innovation was the Active Service System (ASSYST) which improved economy through continuously analysing oil quality in the engine. By doing this, the system made it possible to have need-based maintenance intervals that matched actual operating conditions, thereby extending the standard interval from a fixed 15,000 km to an average 20,000 km.

Safety-related interior touches were also of the customary Mercedes-Benz standard. Height-adjustable automatic seat belts with belt tensioners and belt-force limiters on the front seats came as standard, as did driver and front passenger airbags and, for the first time in a cross-country vehicle, side airbags in the front doors.

The M-Class complied with passive safety requirements that came into force in the European Union in 1998, as well as with regulations enacted at a later date in the USA. Of course, the model series also met the ambitious standards set by Mercedes-Benz internally. From the concept phase onwards, the chassis frame was designed specifically to optimise its behaviour during frontal, rear and side impacts. The objective was to allow a predetermined, maximum deformation of the vehicle while maintaining the stability of the passenger cell, in order to guarantee that occupants experienced the lowest possible loads within a sufficiently large survival space during a collision. Consideration was also given to protection for other road users. This was a subject of intensive research at Mercedes-Benz and was being implemented increasingly through improved vehicle compatibility. M-Class vehicles had a low front-end structure that deformed in a controlled manner, combined with a low-slung frame. This meant they were also able to absorb the impact energy of the other vehicle involved in a collision, thereby mitigating the loads experienced by occupants of smaller vehicles, who would otherwise have been at a disadvantage.

In the USA and Canada, the model series was launched in 1997. First on the market was the ML 320, fitted with the same 3.2-litre engine used in the E-Class and CLK, which in the M-Class delivered 160 kW (218 hp) and was partnered with an electronically controlled, five-speed automatic transmission as standard. The M 112 engine series featured an all-new V6 design incorporating a raft of game-changing innovations, including three-valve technology, dual ignition and low-friction, light-alloy cylinder liners. This engine was manufactured in the state-of-the-art Bad Cannstatt engine plant which officially opened six weeks before the Tuscaloosa plant on 9 April 1997 under the moniker “Factory of the Future”.

March 1998 saw deliveries start in the European market, where a cost-effective, entry-level model with a 2.3-litre four-cylinder in-line engine was offered alongside the ML 320. This 110 kW (150 hp) unit was also drawn from the standard Mercedes-Benz engine line-up and was already a proven force in the C-Class and E-Class. The ML 230 was offered with a five-speed manual gearbox as standard, but, unlike its more powerful counterpart, it did not come with air conditioning as part of the basic equipment.

In January 1998 Mercedes-Benz presented the ML 430, the most powerful M-Class variant yet, at the North American International Auto Show in Detroit. Inheriting the same powerful 199 kW (270 hp) 4.3-litre V8 engine with three-valve technology and dual ignition already featured in the E-Class from September 1997, this was the new top-of-the-range model in the series. As well as an electronically controlled five-speed automatic gearbox, the standard equipment included the 4ETS all-wheel-drive system, which in the ML 430 was combined with ESP® driving safety and BAS brake assist systems. This same combination appeared in the ML 320 from September 1998. Leather appointments, air conditioning and seat heating completed the standard ex-factory configuration. To signify its position as the top model, the M-Class ML 430 boasted bumpers, side skirts and side rub strips painted in vehicle colour and redesigned 17-inch wheels shod with 275/55 R 17 tyres. Market launch in Germany took place in 1999.

As early as January 1999 a jury comprising 22 international motoring journalists had awarded the M-Class the coveted “World Car Award” at the Geneva International Motor Show. This special award was given to the car deemed to be most suitable for all five inhabited continents of the world. A majority of the top journalists from America, Europe, Africa, Asia and Australia who took part in the survey ranked the innovative all-activity vehicle from Mercedes-Benz in first place by a substantial margin, thereby making it the clear choice for the ideal global car. These independent experts particularly praised the unique combination of flexible utility, compelling value for money, exemplary safety, forward-looking design and superb off-road capabilities in conjunction with the road-going qualities of a saloon car.

Autumn 1999 saw the M-Class join the diesel age with the introduction of the ML 270 CDI. Using the same 120-kW (163-hp) five-cylinder CDI engine introduced in the E-Class a short time earlier, superior performance together with good fuel economy was now a reality. The diesel model replaced the ML 230 as the M-Class entry-level model. Common-rail direct injection, four-valve technology, an intercooler and a VNT turbocharger with variable turbine blade geometry all helped to distinguish the ML 270 CDI engine. A new six-speed manual gearbox was paired with the five-cylinder engine as standard. Rated at 120 kW (163 hp), the engine was capable of delivering a maximum 370 newton metres of torque between 1800 and 2600 rpm. When combined with the optional five-speed automatic gearbox, this figure increased to 400 newton metres. In addition to outstanding in-gear acceleration at low and medium engine speeds, the qualities of the CDI engine were readily apparent at the fuel pump. Fuel economy of the ML 270 CDI with manual transmission in the New European Driving Cycle was a low 9.4 litres of diesel per 100 kilometres, and just 9.3 litres with automatic transmission.

In parallel to the ML 270 CDI, Mercedes-Benz also introduced a new flagship model to the series in the shape of the ML 55 AMG. At the start of the 2000 model year, this new eight-cylinder version was the jewel in the crown of the M-Class range. Packing a powerful 255-kW (347-hp) V8 engine, high-quality interior touches and attractive body design features, the AMG-refined off-roader defined a new top segment in its vehicle class. Benchmarks were redefined by the levels of comfort, safety and dynamism found in the ML 55 AMG.

Originally featured in the S-Class, the 5.0-litre, eight-cylinder engine was modified by the engineers at Mercedes-AMG to incorporate a revised crank assembly, special oil-spray nozzles and high-performance camshafts originally designed for motorsport. Combined with an enlarged displacement of 5.5 litres, these measures helped the V8 engine serve up a formidable maximum torque of 510 newton metres from as low as 2800 rpm. Acceleration and speed measurements were impressive too. In the 0 to 100 km/h sprint, the ML 55 AMG crossed the line in just 6.9 seconds, while its top speed was clocked at 232 km/h. A high level of handling safety was provided by wide-base tyres of size 285/50 R 18 and ESP® Electronic Stability Program, which ran hand-in-hand with all-wheel drive and recalibrated axles.

Various harmoniously integrated design elements also helped the ML 55 AMG draw attention to its solitary poise. Twin power domes on the bonnet provided a particularly striking statement of the vehicle’s sporty and dynamic nature. Typical Mercedes elegance was also part of the ML 55 AMG formula, with understated chrome trim embellishing the radiator grille. Specially designed bumpers were painted in vehicle colour. Side skirts and painted wheel-arch flarings ensured that the off-roader advertised its muscle when viewed from the side too. These detachable parts created space for sporty 18-inch tyres and lent the body a wider, more powerful visual appeal. This augmented the performance-focussed overall look which was matched perfectly by the attractive five-spoke AMG light-alloy wheels (9 x 18 J ET 52). At the rear, the new top-end model boasted specially designed bumpers painted in vehicle colour and two chrome-finish exhaust tailpipes that discreetly alluded to its Mercedes-AMG provenance.

Inside the ML 55 AMG, occupants luxuriated in sports seats with supple buffalo leather covers, surrounded by dark-brown burr-walnut wood trim and high-quality velour carpets. In the cockpit, the tone was set by an instrument cluster with pale dials, an ergonomic wood/leather sports steering wheel, leather armrests between the front seats and chrome surrounds on both the cockpit instruments and the controls for the standard-fit air conditioning. Also included in the standard equipment were xenon headlamps with high-pressure cleaning jets, power front sports seats with memory function, a power tilting/sliding glass sunroof, side airbags for front and rear passengers, an MB Audio 30 stereo car radio, a sound system and power side windows in the rear.

For those who wanted a more personalised M-Class experience, from autumn 2000, Mercedes-Benz offered a dedicated designo range for the W 163. The designo packages were available for all M-Class model variants, including the top-of-the-range ML 55 AMG V8. Included in the selection was high-quality poplar wood trim, with designo anthracite and designo natural colour options which harmonised particularly well with the new two-tone designo leather appointments. Leather for the interior was available in three designo colours – ultramarine, dark green and brown – which could be combined with the standard anthracite appointments. To complement the java interior colour option offered with the ML 270 CDI, ML 320 and ML 430 model variants, the Mercedes designers developed the designo borneo colour. The designo leather colours featured in the centre sections of the seats and door panelling, the door handle trim, the steering wheel and the automatic selector lever. Anthracite and java interior colours appeared in the fine nappa leather seat side bolsters, the border around the shift gate and the armrests between the front seats. Front head restraints were embossed with designo lettering, velour floor mats had coloured designo leather-reinforced edges, and seat side bolsters were decorated with double topstitching in the same designo colour.

In autumn 2001 the facelifted first-generation M-Class appeared on the market. Better safety, improved dynamics and even more fun at the wheel – these were the most important goals of the product evolution. Mercedes-Benz added significant value to the attractive and very successful all-wheel-drive car, with changes to the design, interior, technology and standard equipment to match the needs of their customers even better than before. A total of over 1100 completely new or modified components were used for this comprehensive facelift.