New Mercedes S-class: a technical tour de force

War, scandal, wardrobe malfunctions and a car that can drive itself are the stories that will have the news desk banging on your front door. Yet my door remained strangely silent after being given an insight (and virtual drive) in Mercedes-Benz's new S-class, which debuts next year. That's because, while this flagship model could potentially have been the world's first autonomous driving car, Mercedes has decided not to give it that capability – the driver's hands have to remain on the wheel.

Not that this teutonic monster couldn't drive itself. "The car would do it [autonomous driving] today," said Jochen Haab, technical support manager. "We have had test cars doing that, but what happens if a child steps out into the street and the radar misses it?"

Many experts have predicted that limited driving autonomy will be introduced in luxury cars during the next decade. Mercedes had dropped a few hints that the new S-class would be in the vanguard of this development. It's new Distronic Plus steering assistance system gives it the potential. It has a lane-guidance capability, which locks on dotted white-lane markings, or the car in front on motorways at speeds up to 124mph with corners of less than 15 degrees.

With this steering assistance plus the new sensors and safety algorithms, the S-class can maintain its distance from the car in front, braking to a complete halt, restarting from stationary and even stopping for cross traffic. But the driver has to keep hold of the steering wheel and, if the system detects that he isn't imparting torque to the steering-wheel rim, then it will warn after 10 seconds and switch the system off after 15.

So what happened? We had been given to understand that a limited degree of autonomy had been planned, but only at low speeds on motorway jams, where traffic is travelling predictably in the same direction at similar speeds, with no pedestrians or junctions. "For sure there was a debate about it," admits Haab, "but what if you have an accident?"

He says that product liability issues and potentially expensive legal claims against Mercedes were big disincentives, but there were other considerations. "We would have to have full data recording on board," he said, "and would our customers be willing to accept such a system?"
In addition there were issues about the technology's ability to maintain autonomous driving in all circumstances. "Can the car detect whether it can drive autonomously for the next 20 seconds?" said Haab. "Probably not at the moment."
Distronic Plus relies on a new 360-degree sensor comprising six separate radar systems, a stereoscopic camera, 12 ultrasonic sensors and four additional cameras. The stereoscopic camera recognises the speed and trajectory of moving hazards up to 164 feet away and can detect cross-traffic cars and pedestrians. A two-stage infra-red detection system sees hazards in the dark and advanced computer algorithms can identify and differentiate humans from animals and will brake for both, but flash its headlamps in warning only at humans.
While the decision not to launch a full autonomous driving mode will be seen as a prudent decision in some quarters, it is still a lost opportunity. General Motors' Cadillac division has a self-driving system on test known as "Super Cruise" capable of fully automatic steering, braking and lane centring on highways under certain conditions. According to Nady Boules, GM's director of electrical and controls integration research, autonomous driving cars will be on sale within 10 years.

We were allowed to drive the new Distronic Plus system at Mercedes-Benz's driving simulator in Sindelfingen, Germany. This massive installation allows computer-generated 360-degree views from a real car installed in the hydraulically powered pod, which has a 40-foot base on which it is able to react realistically to acceleration, braking and cornering inputs. Unsurprisingly our car reacted perfectly in our short urban "drive", with sensors detecting cars crossing our path against the traffic lights and pedestrians stepping out into the road.

Engineers admit there are still issues with the system, however, including fog, which is almost impossible for the sensors to see through and computer algorithms that are still far from perfect.
But even if it doesn't drive on its own, at least the new S-class will have the world's most advanced headlamps. Mercedes claims it will be the first car without a single light bulb, although since Karl Benz's 1886 Benz Patent Motorwagen appeared 13 years before Thomas Edison first patented the electric light bulb, that's highly debatable. The S-class's light-emitting-diode-based lighting system is, nevertheless, a world first and allows the lamps and indicators to be dimmed at night or when stationary in traffic. It's more complicated than that, though...
Each three-motor headlamp unit is fitted with an active masking system for the high-beam function. Using the car's advanced sensors, the car recognises the headlights of oncoming traffic, or tail lamps of cars in front. It then actively vignettes the high-beam around those cars so their drivers are not dazzled by the S-class's lamps.

Mercedes claims that the system is so effective that on the open road, drivers should be able to stay on full beam virtually all the time.
This option is predicted to cost no more than a Bi-Xenon headlamp system and the total energy requirement of the LED headlamps in the new car is just 34 watts compared with 120 watts for halogen lamps and 84 watts with Xenon lighting, which saves 2.1g/km of CO2. The LED lighting also has a better colour balance, appearing white instead of the blue white of some Xenon systems.