Musk has complained that U.S. regulations are too onerous and are holding back the development of self-driving cars. Ethics experts are worried that once President-elect Donald Trump takes office, Musk will push him to ease oversight of Tesla, which just suffered its first decline in annual sales in more than a decade.

A potentially faulty driverless car feature found in roughly 2.6 million Tesla cars on U.S. roads highlights the risks associated with CEO Elon Musk's plans to roll out unsupervised Full Self-Driving this year.

The “Actually Smart Summon” feature enables drivers to remotely summon or move their vehicles to them or another location via a mobile phone app.

The agency has previously looked into other iterations of Tesla's Summon self-driving option.

The National Highway Traffic Safety Administration announced it is investigating nearly 2.6 million Tesla vehicles over a remote driving feature.

U.S. regulators on Tuesday announced an investigation into 2.6 million Tesla vehicles following reports of crashes linked to technology that enables drivers to use a smartphone app to remotely summon their cars or direct them to another location.

The National Highway Traffic Safety Administration (NHTSA) is investigating 2.6 million Tesla vehicles due to reports of accidents related to the Smart Summon and Actually Smart Summon features.