First Ride: 2018 Mercedes-Benz S-class Prototype, Now More Semi-Autonomous Than Ever

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When the 2017 Mercedes-Benz E-class debuted last year, it broke with tradition by its inclusion of a new-to-Mercedes suite of semi-autonomous hardware and capabilities. This was strange because, for decades, every new technology to spring from Benz’s imagination—from stability control to adaptive cruise control to night vision—has first made its debut on the flagship S-class. Now equilibrium returns, because the 2018 S-class sedan is adopting the E-class’s Drive Pilot driver-assistance features and expanding on them. We had the opportunity to sample the tech during a ridealong in a prototype in Germany before the car is unveiled later this year.

For those unfamiliar with the E-class’s semi-autonomous driver-assist technologies, they include adaptive cruise control, a lane-keeping setup that can handle some steering duties and autonomous lane changes, and a 360-degree array of radar and ultrasonic sensors for keeping track of lane markings, other cars, and road signs. In Mercedes parlance, this cocktail is referred to as the company’s Generation 4 driver-assistance tech. The current S-class makes do with Generation 3 gear, which means it also has adaptive cruise control that can bring the car to a stop, albeit mixed with lower-bandwidth lane-keeping assist and fewer sensors. That changes with the 2018 S-class, which leapfrogs the E-class with Generation 4.5 equipment and software.

According to Mercedes, the hardware installed on the revised S-class is more or less the same as the sensor package on the E-class. What adds the “.5” to its generation name is newer software; it makes for a smarter lane-change feature and smoother, newly map-based adaptive cruise control. Because Mercedes just loves to assign wordy names to its tech, the upgraded features are called Active Lane Change Assist and Active Distance Assist Distronic.

2018 Mercedes-Benz S-class

Where the S-class’s Active Lane Change Assist differs from its E-class counterpart is its ability to merge more deftly into an adjacent lane. Oh, and initiating an automatic lane change now requires a single tap of the turn signal stalk, as one might use for a three-blink-to-pass signal. The system will attempt to change lanes within 10 seconds of a driver’s request and now shows that a lane change is being attempted via graphics in the digital gauge cluster display. As on the E-class, Active Lane Change Assist can be turned off—it is available whenever Active Steering Assist (which is lane-keeping assist) is activated—and, unlike Tesla’s system, it has a rear-facing radar module for tracking faster-moving traffic in adjacent lanes.

2018 Mercedes-Benz S-class

As for Active Distance Assist Distronic, it has a new trick up its sleeve: the ability to use map data to slow the S-class from the driver-set cruise-control speed for corners and roundabouts, instead of only reacting to objects or other cars ahead. Mercedes is cashing in on its investment in Nokia’s Here map data—an investment made alongside several other automakers—putting the data’s speed limit, road curvature, and other information to work informing Distronic. The goal is greater comfort and a more natural-feeling experience with adaptive cruise control.

On curvy country roads or when approaching a roundabout or an exit ramp, the computers will slow the S-class to a speed deemed appropriate—i.e., a low enough speed not to alarm passengers. It’s critical to note that throughout such maneuvers, the driver is handling the steering. Even if the Active Steering Assist function is enabled, it generally won’t handle the sort of tight-radius curves that Active Distance Assist is reacting to.

2018 Mercedes-Benz S-class prototype

Amusingly, Mercedes has tuned Active Distance Assist Distronic to change its behavior depending on the selected drive mode. Leave your S-class in Comfort mode, and speed adaptations for curves and turns are gentle; flick over to Sport mode, and the system brakes later and accelerates back to its set speed with more aggression. During our ride in a camouflaged 2018 S600 Maybach prototype, the speed adjustments were preternaturally smooth, even in the spicier Sport setting, and it really felt as if a (good) human driver were manning the pedals.

The system works best when a destination is plugged in to the navigation system. It will slow for exit ramps, turns, and roundabouts along the route, but it still functions (somewhat less sharply) with no destination set thanks to the onboard Here map data. To prove this, the German engineer we rode with flicked on his turn signal when approaching an off-route side street, and the car began to slow in anticipation. Curious where the map data is stored? It’s downloaded into the car’s computer, although it will occasionally receive over-the-air updates as they become available.



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If there’s a downside, it’s that the car has no way of responding to, say, other cars in a roundabout until it’s behind them. As a result, our driver always had his foot over the brake pedal when approaching circle interchanges and on one occasion needed to intervene to keep the S-class from getting intimate with the side of a hatchback. Oh, and the system can’t read traffic signals or respond to stop signs and the like, so driver involvement remains necessary as freeways give way to more ad-hoc traffic scenarios on back roads or suburban lanes. Also, if anyone out there was a fan of the long-serving cruise-control stalk that poked from many a Benz’s steering column, prepare to mourn: The controls for Distronic have been moved to the steering wheel.

This probably seems like a lot of milk spilled over not much cereal, but Mercedes seems comfortable eking out incremental enhancements to its semi-autonomous features. It wants to build consumer confidence and exposure to the technologies and their interfaces. To wit, not only will the S-class’s Drive Pilot features do more than those in the E-class, but their whereabouts will be easier to monitor. New gauge-cluster icons show when an active lane change is happening and whether the adaptive cruise is slowing the car for slower-moving traffic ahead or an upcoming corner.

As to the 2018 S-class’s other changes, Mercedes will release more information in April at the New York auto show.

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