San Francisco-based startup Scale has raised $18 million for its system that labels autonomous car data quickly and accurately. : Autonomous cars need data. Lots of data. According to research conducted by the Rand Corporation, they’ll have to drive hundreds of millions or even billions of miles to demonstrate their safety. Companies like Waymo are well on their way; the average self-driving vehicle is projected to generate more than 300 terabytes per year. But collecting data isn’t the only technical hurdle. Labeling it — that is, adding the markup that allows cars’ computer models to recognize and learn from it — is another.