I spent about three hours this weekend driving a 2015 Mercedes S550 along a busy interstate. The car was equipped with Distronic Plus and whatever MB calls its lane guidance system. I have to say that it worked very well. I intentionally steered the car towards the road shoulder a few times, and received an audio spanking as the car simultaneously applied gentle braking and steered the car back into the middle of the traffic lane. The Distronic Plus worked very well in keeping a fixed interval from the four-wheeled vehicles in front of me, but was a little less predictable when a narrow vehicle such as a motorcycle was ahead.

I'm guessing that these systems are about a decade or so from being truly foolproof, but they're not bad today. For now, don't try to use your iPad to catch up on your email from behind the wheel...