Power And Pre-Safe
by Malcolm Baylis (12 Sep 02)

It may take only seconds for a driver to be hurtling into a serious crash, but that is still long enough for an amazing protection system developed by Mercedes-Benz to "throw" an embracing safety blanket around the car's occupants, hopefully saving them from more serious injury.

Ironically, to really appreciate how the system works you need to experience it in a false crash situation. And that is what Mercedes laid on for motoring journalists from throughout the world at an airstrip in Germany.

The system is simply called Pre-Safe. It comes into play when hard braking suddenly becomes necessary and the car goes into violent oversteer-and-understeer mode. Frightening whenever experienced, worrying even in controlled situations.

But Pre-Safe is a far cry from simple life-saving manoeuvring while at the wheel. Electronic wizardry takes over in milliseconds, and is capable of interpreting emergency braking and sudden steering movements, then preparing the car's occupants for impact.

As a passenger in a Merc S-Class 600, an extremely large and expensive executive saloon driven by one of the company's many experienced vehicle testers, I was driven at high speed into an emergency braking situation. As the ABS anti-lock braking system juddered into action and the car stood on its nose, so I became aware that the seatbelt had tightened into a real bear-hug, keeping me tight in the seat. There had been no collision, but the car's electronic brain had recognised a potential crash and triggered the procedure of keeping me safe. Had there been a frontal impact then the airbags would also have inflated.

Even More Than That

But as well as clamping me into my seat, the brain had automatically closed the open sunroof because of the potential danger of roll-over, and adjusted my seat back into a safer raised position. Also, had there been rear seat passengers, these too would have been clamped and their seats repositioned to a safe position.

Once the sweaty-palm drama is over, the seatbelts relax their grip and all the other settings, the seating position and sunroof, can be returned to normal. At the same time Pre-Safe is automatically returned to its waiting-for-an-accident-to-happen mode.

The new safety system is based on the findings of Mercedes-Benz researchers, that in nearly 60% of all car accidents there is a pre-crash phase of between 300 milliseconds and three seconds, a relatively long time lapse between an impending collision and the impact itself.

Although it has taken about six years of intensive development work to produce Pre-Safe, engineers found that the minute window of seconds was in fact long enough to fill, and so provide yet another safety feature that puts the German manufacturer ahead of its competitors.

Pre-Safe is also clever enough to judge how severe the collision is, using sensors belonging to the car's electronic stability programme and to the brake assist system.

On top of that, sensors at the front of the car body decide whether to trigger one or both airbags fitted to protect the passenger. It is these same sensors that activate the seat belt tensioners even earlier.

The Latest Engines Too

Mercedes also used the safety day to introduce a new 12-cylinder, twin-turbo engine (pictured) developing 500hp to the range, one of the most powerful engines in its class. It develops 590lb/ft upwards of just 1800rpm, and can hurl the flagship S600 from 0-62mph in 4.8 seconds.

The well-tested six cylinder S-Class engines have also been improved, receiving increases in both power and torque. Displacement of the V6 petrol engine has been boosted to 3.7 litres, adding a 12.5% increase in output to 245hp, and a 13% increase in torque to 258lb/ft at 3000rpm. The modified six-cylinder turbo diesel engine is one of the second-generation Mercedes-Benz common rail units. Its output too has been increased, to 204hp, while maximum torque is now 368lb/ft at 1800rpm, yet fuel consumption is around 4% less than before.

As well as changes under the bonnet, there have been a few changes made to the car's external appearance. The front bumper has a restyled lower air intake to give the body a wider, more powerful look. The radiator grille has been redesigned, and is now taller and steeper. Headlights have been changed, too, with clear lenses and high-brilliance reflectors, while mirror casings and rear lights have also been restyled.

Depending on the model, there are more than 40 changes made to the interior, including chrome embellishments on some select wood trims, upgraded seat upholstery as well as new-look switches. There's a chance to go a step further by adding the optional "designo couture" interior trim which includes finest quality nappa and nubuk leather upholstery, anthracite-coloured polar or maple wood veneer, and a roof lining of fine Alcantara.

All models within the S-Class range are also getting COMAND, the Cockpit Management And Navigation Display system, combining new wide-screen GPS satellite navigation, and a revised audio system that before was available only on the S500 and above.

Seats in the S-Class have also been extensively revised, with the option of a multi-contour design with air chambers automatically inflated or deflated to provide lateral support for driver and passenger when cornering. A special microprocessor inside the seats takes a split-second to decide which airbags should be inflated to provide body support when the car is cornering.

The revised S-Class range goes on sale here next month. Prices start at £44,410 for the S280 and top out at £87,580 for the S600 long-wheelbase model.

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