To explain, let's take a look at the only car on the US market with production gesture controls, the BMW 7 Series. We brought it in for our annual Tech of the Year award. The system allows the driver to adjust volume, take calls, and jump to preferred infotainment functions with a variety of twists, jabs, and swipes. It seemed to function as advertised, and you never had to press a button. But think about all of those motions. They all involve moving your whole arm around the middle of the car. How is that easier than reaching and tapping a screen or grabbing a knob, or better still, moving your thumb an inch on the steering wheel to press a button?
Aside from requiring more effort, gesture controls also lack the precision and positive feedback of more traditional controls. Take adjusting volume for example. With a knob or buttons, it's obvious that one click of the wheel or press of a button is equivalent to the smallest increase in volume available. When twisting your hand, 5 degrees of twist might increase the volume by one level, or it might require 10 degrees. It would also be easy to go too far in adjusting volume with gestures because of this, and because few of us have precise control of our free-floating hands, particularly in moving vehicles. Then you have to twist back and forth getting the volume just right for a full 30 seconds rather than the 5 it would've taken to use the knob.
"But, Joel, how can you rule out this technology when there's only one car with which to try it?" I can do so because Microsoft tried it with video games, and it didn't work too well. In the midst of the motion-control fad following the introduction of the Nintendo Wii, Microsoft launched Kinect for Xbox 360, and later the Xbox One. It went beyond motion-sensing controllers to a camera that could detect your body motions. The technology was impressive, but it suffered from all of the same issues I listed above. It required more effort, but without the precision that actual buttons and control sticks offered. And when you're playing competitive multiplayer in Call of Duty or Halo, speed and accuracy are way more important than using a futuristic control scheme.
This also touches on one last issue with gesture controls. Just as you wouldn't want fussy controls getting in the way of your high-stakes gaming performance, you wouldn't want them getting in the way of your even-higher-stakes driving. I can see gesture controls being a real distraction. Let's go back to the volume adjustment example in which using gestures might take 30 seconds as opposed to 5 with a knob. At highway speeds, 30 seconds is a long time to have your attention split, let alone being fully engrossed in activity that isn't driving. You can cover half a mile in that time at 60 mph, and not paying full attention could result in a crash.
To recap, gesture and motion controls require more effort, are less precise, and are potentially distracting and dangerous. None of that is positive, least of all in a car. So for the benefit of everyone, let's let gesture controls die.