The new Mercedes-Benz SL coupe/roadster, which makes its public debut at a press launch in Hamburg today and goes on sale across Europe inthe autumn and in the U.S. next spring, features the motor industry's first electronic brake system.

The brake pedal on the first version to be revealed, the SL500, works with a computer that tells four fast-acting valves exactly how hard to apply the brakes on each wheel.

A backup hydraulic master cylinder comes into play only if there's a serious problem or electrical failure.

In a split-second, the system can change brake pressure on each wheel over uneven surfaces and can increase brake pressure on just the outside wheels when braking in turns, taking advantage of the higher loading during cornering.

Mercedes-Benz says that the ABS anti-lock and ESP stability control work more efficiently since they are more deeply integrated with the brakes, instead of functioning as parallel systems.

An electric hydraulic pump and a high-pressure reservoir (accumulator) provide 'always-on' full brake pressure at each wheel.

The computer-operated modulator valves control how much pressure actually operates the brakes at each wheel. In this new system, the conventional, bulky vacuum brake booster is now obsolete.

If the driver switches his foot quickly from accelerator to brake pedal, the electronic brake system recognises the early signs of an emergency situation and reacts automatically.

With the help of the high-pressure reservoir, the system raises the pressure in the brake connectors and instantaneously moves the pads onto the brake discs, which can then spring into action with full force as soon as the brake pedal is pressed.

At highway speeds, this pre-loading of the braking system reduces stopping distance by about three percent.

The SL500 features the motor industry's first electronic brake system

In addition, the system automatically senses when the road is wet and imperceptibly applies the brakes just enough to keep the discs dry, so that brake operation remains fast and consistent in the rain.

The new braking system stars in an all-new SL range which is only the fifth generation of a line which began in 1954 with the legendary 'gullwing' 300SL.

Other technological features include ABC active suspension and ESP stability control.

The new SL also features an SLK-style retractable hardtop that combines the benefits of both a convertible and coupe in one car.

However, the new SL500's retractable hardtop can be fully opened or closed in just 16 seconds compared with 25 seconds for the SLK's lid.

The SL roof is also a completely new design which operates in a different manner. As the power roof retracts, the rear window glass also rotates so that its curvature nestles inside the stowed roof panel, providing a much larger cargo area of 6.8 cubic feet.

With the top up, the boot holds 9.7 cubic feet - over 1.8 cu. ft. more than its predecessor.

A hydraulic pump and 11 computer-controlled hydraulic cylinders power the system. As in the SLK, the new SL's top is controlled by a centre console switch.

When the top is stowed, pressing a red button located inside the trunk raises the folded roof about 20 degrees, making cargo access easier.

The 500SL's five-litre V8 engine produces 302 horsepower, accelerating the new model from 0 to 60 mph in approximately six seconds.

Twin sparkplug, three valves-per-cylinder technology also means the new car qualifies as an Ultra Low Emission Vehicle in the U.S.

The new SL features a light weight body with the bonnet, doors, boot lid and roof all made of aluminum. The bonnet alone is 33 pounds lighter than a comparable steel hood.

Over 30 percent of the body structure is made of high-strength steel, so that the body is 20 percent stiffer than the previous model's with the top down and the drag coefficient is 0.29 - over nine percent lower than before.

The latest SL, which will be launched early in 2002 as a 2003 model in the U.S., features new head/thorax side airbags in the doors as well as two-stage front airbags that deploy with partial force in less severe collisions and with full force in more serious impacts.

The airbags are designed to work in concert with the three-point seatbelts, which are equipped with tensioners that remove belt slack in a collision as well as belt force limiters that help prevent seatbelts injuries in severe impacts.

Following on from the pioneering automatic roll bar for the previous SL, the new car model has a similar bar which pops up in 0.3 of a second when its electronic control senses an impending rollover.

As before, the shoulder belt is anchored directly into the seat back, ensuring good seatbelt geometry regardless of seat position and providing an extra measure of protection in the event of a rollover.


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