Inside Tesla as Elon Musk Pushed an Unflinching Vision for Self-Driving Cars

Elon Musk built his electric car company, Tesla, around the promise that it represented the future of driving — a phrase emblazoned on the automaker’s website.

Much of that promise was centered on Autopilot, a system of features that could steer, brake and accelerate the company’s sleek electric vehicles on highways. Over and over, Mr. Musk declared that truly autonomous driving was nearly at hand — the day when a Tesla could drive itself — and that the capability would be whisked to drivers over the air in software updates.

Unlike technologists at almost every other company working on self-driving vehicles, Mr. Musk insisted that autonomy could be achieved solely with cameras tracking their surroundings. But many Tesla engineers questioned whether it was safe enough to rely on cameras without the benefit of other sensing devices — and whether Mr. Musk was promising drivers too much about Autopilot’s capabilities.