A Newport Beach resident is suing Hyundai Motor and the air taxi startup Supernal it backs, accusing them of retaliation after she complained about alleged investor deception and gender discrimination.
Diana Cooper, who joined Supernal in 2020 as the company’s sixth employee, says she was harassed, marginalized and underpaid, according to a complaint filed Oct. 17 with the Superior Court of California.
One of several young companies racing to achieve electric air mobility in California, Supernal is backed by Hyundai and affiliated with Hyundai Motor America. The Irvine-based company is developing a battery-powered, vertical takeoff and landing air taxi.
Shortly after launching, Supernal recruited Cooper for her expertise in emerging aviation policy.
Supernal retaliated against Cooper when she raised alarms about misleading investors, the lawsuit said. In 2023, Cooper shared concerns that Supernal was advertising an unrealistic entry timeline for its technology.
The case also says she complained about the “pervasive, misogynistic culture” at the company, where executives made offensive remarks about hiring “$5,000 hookers” for clients.
The retaliation against Cooper was “swift and systemic,” her lawyers wrote. Cooper was excluded from meetings with Hyundai executives and was barred from traveling to Hyundai’s headquarters in South Korea.
Also in 2023, Cooper and other senior female employees were expelled from the company’s quarterly business review meeting, according to the complaint. When Cooper raised concerns over the exclusions, Hyundai Motor’s chief financial officer said the company “doesn’t care about diversity, equity and inclusion.”
Cooper faced other harassment from colleagues, including comments about her body, the complaint said, and an incident in which a male colleague showed Cooper a video of him having sex.
During her time at Supernal, Cooper said, she was underpaid compared with her male colleagues and was persuaded to relocate from Washington, D.C., to Newport Beach with false promises of a promotion.
After Cooper’s leadership role at Supernal was stripped away in April 2025, she reported widespread mismanagement and unethical conduct at Supernal directly to Hyundai Motor’s executive chairman.
Hyundai opened an investigation into Cooper’s claims but did not offer any protection from retaliation, according to the case.
There was later a 3½-month legal investigation into conduct at Supernal, which led to the firing of Supernal’s chief executive and chief technology officer.
Hyundai Motor said that requests for comment could be directed to Supernal. A spokesperson for Supernal said the company had no statement on the matter.
Cooper remains on medical leave after suffering severe emotional distress stemming from Supernal’s actions, the lawsuit said.
