A self-driving car is, in the words of the roboticist Missy Cummings, "one, big data-gathering machine." Which, on one hand, is great: For driverless cars to work, they have to slurp up huge streams of sensory data about the world around them. But these vehicles will also collect reams of personal information about their passengers--just the way Uber and Google Maps have detailed information about where you've gone, and can predict where you're going. This isn't necessarily bad--there are all kinds of neat services that might rely on personalized data--but it does raise the question of how, if at all, data collection ought to be regulated. This topic came up last week at a Congressional hearing on driverless cars, and the companies potentially doing the data-collecting were, and this is putting it gently, evasive.