Is the new Mercedes-Benz E-Class a self-driving car or isn’t it?

In the midst of a national debate about the limits of autonomous technology, Mercedes has launched an update of its E-Class sedan with a new generation of driver-assistance technology called Drive Pilot. The company is marketing the system with a slick advertising campaign that delivers a mixed message that doesn’t quite jibe with its actual functionality, as we experienced with our testing.

Much of the public concern up until now has been focused on electric carmaker Tesla after a few accidents involving its semi-autonomous Autopilot system. The National Highway Traffic Safety Administration (NHTSA) and National Transportation Safety Board (NTSB) are investigating one of these crashes, which resulted in a fatality in May in Florida.

While there are many aspects to Autopilot that we find promising, Consumer Reports has called for Tesla to disable the Autosteer functionality of Autopilot until it can be reprogrammed to require drivers to keep their hands on the wheel.

That background has made Mercedes’ ads, launched in late winter, all the more jarring. In one commercial, the narrator says, “what it means to be self-driven,” and the driver removes his hands from the wheel. In another, the narrator says, “introducing the 2017 E Class from Mercedes-Benz, a concept car that’s already a reality.” Again, the driver takes his hands off the wheel.

Mercedes in an email response to Consumer Reports’ questions said, “The only reason the driver’s hands are not on the wheel is so that viewers can see that the wheel is moving on its own to correct (e.g. the vehicle is cross lane lines with no positive input from the driver indicating intent to change lanes).”

It added that the commercials are “futuristic portrayals,” and that “for the here and now, we have always stressed that our technology is designed to assist the driver, not to encourage customers to ignore their responsibilities as drivers.”

But safety advocates including Consumer Reports on Wednesday sent the Federal Trade Commission a letter [PDF] calling on the agency to investigate the Mercedes ads. The letter cited the ads' potential to mislead consumers into thinking that the vehicles can drive on their own, when in fact the cars come with frequent reminders for consumers to keep their hands on the wheel.

While the ads portray people taking their hands off the wheel, our testing found that Drive Pilot actually is an effective aid for drivers.

Like Tesla’s Autopilot, the Mercedes system modulates speed, keeps the car in its lane, and even changes lanes automatically.

Drive Pilot allowed us to stay in control of the car, but offered an assist to keep the car in its lane. With the system engaged, we could still steer the car and even change lanes, though we did feel variable resistance when approaching lane markings. We found it easy to drive the car in this mode, and believe it could help a tired or distracted driver stay safe.

Also like the Tesla system, Drive Pilot allows drivers to take their hands off the wheel. Drive Pilot warns you to put your hands back on the wheel in 15 to 45 seconds in our testing. We believe drivers should never be able to take their hands off the wheel, but that amount of time is better than the 2 to 3 minutes we’ve experienced with our two Tesla test cars with Autopilot.

The Mercedes system is a contrast to Tesla's Autopilot in other ways, too. As soon as you exert some force on the steering wheel with Autopilot on, the automatic steering system disengages. Tesla has said that drivers should always keep their hands on the wheel, and that Autopilot boosts safety when used correctly.

From our experience with the two systems, it feels as if Tesla’s Autopilot is the car driving itself with you overseeing it, while Mercedes’ Drive Pilot is you driving the car with it overseeing you. And until the technology has evolved more, we believe Mercedes’ concept is the right direction.