DETROIT -- The founder and executive chairman of Fisker Automotive resigned from the green-car startup on Wednesday, citing "several major disagreements" with executive management over business strategy.

Henrik Fisker announced his departure from the maker of the Karma plug-in hybrid in an email. He declined to describe the nature of the disagreements that prompted him to leave the company, which he founded with Barny Koehler in 2007.

He told Reuters in a brief telephone interview that it was a "very tough" decision to make.

His surprise exit comes at a tumultuous time for the Southern California automaker, which is seeking a financial backer and partner to help build its second model, the Atlantic plug-in hybrid. Fisker has not produced a vehicle since last July.

A Fisker Karma luxurious electric car is seen the US car maker’s booth during the 83rd Geneva Motor Show on March 5, 2013. FABRICE COFFRINI/AFP/Getty
A Fisker Karma luxurious electric car is seen the US car maker's booth during the 83rd Geneva Motor Show on March 5, 2013. FABRICE COFFRINI/AFP/Getty Images ( FABRICE COFFRINI )

The automaker is now weighing bids from two Chinese automakers: Geely, the owner of Sweden's Volvo, and state-owned Dongfeng Motor Group, sources have previously said.

At the same time, the company is still a "couple months" away from resuming production of its Karma, the company's flagship vehicle that was designed by Henrik Fisker.

Analysts and consumers have lauded the Karma for its style, but the car has also faced a number of quality issues, including a recall of batteries made by A123 Systems and a scathing review by Consumer Reports last year.

The Atlantic is crucial to helping Fisker regain its footing. The sedan is geared toward families and will be about half the price of the Karma, which has a price tag starting around $103,000.

Initially, Fisker planned to use a U.S. Department of Energy loan to pay for the Atlantic, but last year the agency froze the unused portion of that $529 million loan due in part to a delay in getting the Karma to market.