SpaceX and Tesla Motors Inc. founder Elon Musk believes that most cars won?t have drivers in three years and people will arrive on Mars by 2025. Space Exploration Technologies Corp. could start sending people off-planet by 2024, starting a 26-month cycle that will colonize the Red Planet and form the foundations of a space-faring civilization, the chief executive officer of both companies told Recode?s Code conference.

Regarding autonomous vehicles, safety-prone regulators are the hold-up, the billionaire PayPal co-founder said Wednesday.

"I consider autonomous driving to be basically a solved problem. There?s really only one area where it?s a little dodgy, and that?s where you?re at 30 to 40 miles per hour" in cities, he said. "We?re less than two years away from complete autonomy. Regulators however will take at least another year; they?ll want to see billions of miles of data."

Musk welcomed competition in what he called an increasingly crowded electric and self-driving arena, including from Apple, which he expected to begin producing cars in volume by 2020. The iPhone maker however has never confirmed any plans on that front. Google, which has spent years researching and testing autonomous vehicles, posed no direct threat.

"There?ve been so many announcement s of autonomous EV startups. I?m waiting for my mom to announce one," he said. "Google?s done a good job of showing the potential of autonomous transport, but they?re not a car company."