Technology drives the flagship S-class

Keyless entry, radar braking, ventilated seats, sophisticated telematics, automatic cylinder cut-out… the list of Mercedes S-class features reads like a catalogue of automotive research projects. But Daimler-Benz has managed to bring all this technology into its new flagship luxury model, which goes on sale in Europe later this month. Prof Jurgen Hubbert, Daimler-Benz board member […]

Keyless entry, radar braking, ventilated seats, sophisticated telematics, automatic cylinder cut-out… the list of Mercedes S-class features reads like a catalogue of automotive research projects.

But Daimler-Benz has managed to bring all this technology into its new flagship luxury model, which goes on sale in Europe later this month.

Prof Jurgen Hubbert, Daimler-Benz board member for passenger cars, describes the S-class as a ‘technology showcase’.

‘This is the most important model in the Mercedes-Benz brand,’ he says. ‘No other car has such a halo effect. It shows that we are setting standards at the top of the line.’

Development of the S-class has led to 340 patent applications from Daimler engineers. The most important new feature is the Distronic intelligent cruise control, which keeps the vehicle at the selected safe distance from the car in front.

The system, which will be available from spring 1999, involves a radar sensor in the radiator grille to scan the road ahead of the S-class over a distance of up to 150m.

This uses the Doppler effect to calculate the speed and distance between the two vehicles. If the S-class gets too close to the car in front, the Distronic system will ease off the throttle and even activate the brakes. If the situation is too hazardous, an alarm signal is sounded and the driver has to intervene by using the brakes. The point is that the driver has the obligation to stay alert and in control.

Another S-class innovation is a ‘Keyless Go’ system that allows the car to be operated without keys. Instead, a 4.5mm chip card the size of a credit card will allow the driver both to open the car and drive off.

With the card in a shirt or jacket pocket, the driver has only to touch the door handles of the car (fitted with sensors). Inductive aerials fitted in the doors and rear bumper then send the card signals, which are returned as an identification code by radio. If this code matches the stored value, the car door or boot can then be opened. Once inside the car, the same process takes place when the driver touches a start button on the shift lever, and, if the driver has the chip card, the engine starts up automatically.

The electronics of the S-class are the headline grabbers, but the engineering of the car’s chassis is equally impressive.

Instead of conventional damping with coil springs and gas pressure shock absorbers, the S-class has an AIRmatic system (adaptive intelligent ride control) which combines pneumatic suspension and an adaptive damping system. This can adjust the ride height by supplying or releasing compressed air to the rubber bellows of the pneumatic suspension struts. An adaptive damping system adjusts the stiffness of the front and rear shock absorbers to suit the load, road surface, road condition and driving style.

The S-class’s interior has further innovations, not least the seats. A lumbar support built into the backrest, with air chambers that can be individually inflated with variable pressure, is standard equipment.

Another option is a multi-contour backrest with seven individually adjustable air cushions. The middle of the three lumbar area cushions can breathe, by slowly releasing air and then reinflating again, forcing the spinal column to shift its position slightly, which is good for the back.

As well as giving a massage, they cool you down using ten electric fans concealed in the cushions. These draw in air from under the seat and distribute it over the entire seat surface by plastic channels and a ventilation fabric.

Climate control in the rest of the vehicle is similarly clever. The air-conditioning system has also been designed to identify the position of the sun and concentrate cooling on the section of the cabin most likely to be overheating.

From the outside, the new S-class looks a good deal more elegant than its heavyweight predecessor. The design of the body has shaved a full 300kg from the weight, as well as getting more interior space, despite smaller overall dimensions. At a shade over 5m in length, the S-class is 75mm shorter than its predecessor, as well as being 31mm narrower. The new model uses twice as much high-strength steel and aluminium, both of which reduce weight.

All this translates into what Mercedes believes will be a more attractive car to drive, as well as making it more economical to run. Buyers of the V8-powered S500 will even be able to run the car as a four cylinder unit under light loads, thanks to an automatic cylinder cut-out system that will save about 7% on average fuel consumption.

It is activated when the V8 only has to supply part of its power and torque, for example in urban traffic, on country roads, or when cruising at constant speed on the motorway in the medium range of engine speeds. A conventional eight-cylinder engine would lose efficiency in such conditions due to incomplete cylinder filling and high losses during the gas cycle. In the S-class, the engine management unit deactivates combustion chambers by cutting off the fuel supply and immobilising the inlet and outlet valves.

Occupants do not notice the change, because the engine computer prevents any sudden torque change by changing the throttle valve position and ignition timing. The same procedure occurs when the driver steps harder on the accelerator and the engine has to remobilise its full torque. In a split second, the four silenced cylinders are reactivated.

Compared with its predecessor, the new S-class is leaner and, in many respects, smarter. With 40 on-board computers linked by fibre optic cables, levels of vehicle systems automation never before attempted are possible: rear headrests rise automatically when the rear seatbelts are in use; the headlamps can be set to come on automatically when it gets dark, or if the car enters a tunnel; the telephone and audio controls can be voice activated.

The outgoing model suffered from an image as an over-engineered, heavyweight car that was out of step with a cost-conscious business community. The new S-class, launched as world leaders worry about recession, may be more in tune with its market.