DETROIT — As the co-founder and chief executive of Tesla Motors, the technology billionaire Elon Musk has consistently portrayed his company’s electric cars as cleaner, safer and more innovative than models made by other automakers.

His confidence in Tesla’s technology has seemed boundless, particularly when the company announced last year that it would equip its flagship Model S sedans with a self-driving feature called Autopilot that was still in its testing phase. The technology was so out in front of federal highway regulations that there were no rules against it.

But with the revelation this week that a Model S driver in Florida was killed in May while operating his car in self-driving mode, Mr. Musk’s determination to push limits has hit its most formidable roadblock.

The question now is how much longer Mr. Musk and Tesla can continue to defy auto industry convention in trying to stay so far ahead of the competition. A major point of contention is the Autopilot feature and the decision to make it available to car owners while it was in “beta test” mode — a term typically applied to software that a company releases on an experimental basis.