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

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.

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 is probing about 2.6 million Teslas after regulators discovered that a feature on multiple vehicle models was tied to crashes. The feature, known as "Actually Smart Summon" is intended to have the car park itself and pick up its owner using a button on the Tesla app.