During a quarterly financial call, Tesla CEO Elon Musk has revealed some interesting details about the future of the Model S's Autopilot feature. Most notably, Musk said that "additional constraints" will be added to the activation of Autopilot, to "minimize the possibility of people doing crazy things."

Musk said on the call that around 40,000 Model Ses currently have Autopilot mode available to them. He said those 40,000 cars are logging about a million miles of driving per day—but he didn't clarify if that was the total number of miles driven, or the number of Autopiloted miles driven. In any case, Musk said that the "early data is very positive... we're very aware of many accidents that were prevented by Autopilot, and not aware of any that were caused by Autopilot."

Still, Musk wasn't pleased with "some fairly crazy videos" on YouTube. "This is not good. We will be putting some additional constraints on when Autopilot can be activated to minimise the possibility of people doing crazy things." Musk didn't say when those constraints would arrive, but considering Autopilot is still in beta testing, we'd expect an over-the-air software update sooner rather than later.

Musk declined to say what the additional Autopilot activation constraints might be. Most other cars with semi-self-driving features usually require that your hands stay on the steering wheel, deactivating if you remove your hands. Tesla's Autopilot, however, will continue to automatically steer if you remove your hands. Tesla suggests that drivers keep their hands on the steering wheel when enabling Autopilot, but it isn't currently enforced in software—which may change after Musk's comments today.

The Tesla CEO also said that he was aware of some users experiencing errors with Autopilot, but downplayed their significance. "It was described as a beta release. The system will learn over time and get better and that’s exactly what it’s doing. It will start to feel quite refined within a couple of months." There are plenty of videos of Autopilot errors on the Web. They mostly seem to involve the Model S getting confused and lurching to one side, even on straight roads.

Finally, Musk shifted gears to talk about the future of Autopilot and autonomous cars. If you're not part of the Autopilot beta test, and didn't add the Autopilot package (£2,100 or $2,500) when buying your Model S, "in the coming months" you will be able to do an "in-app purchase" (Musk's words) for £2,500 or $3,000 to enable Autopilot features.

More generally, Musk reiterated his vision for the future: "All cars will be fully autonomous in the long term. I think it will be quite unusual to see new cars that don't have full autonomy in the 15-to-20-year time frame. For Tesla it will be a lot sooner than that. Any cars that are being made that don’t have autonomy will have negative value."