There's trouble a-brewin' in Silicon Valley. Electric car manufacturer Tesla has filed a lawsuit against Henrik Fisker and his company, saying that he stole design ideas and trade secrets.

California-based Tesla contends that Fisker fraudulently agreed to take on a $875,000 contract to design a four-door hybrid - expected to be named the White Star - in order to gain access to confidential information.

It argues that Fisker - whose coachbuilding firm is also based in Southern California - produced substandard work, effectively sabotaging the project, and that he used the cash to develop his own electric car project: soon after working for Tesla, Fisker unveiled his own four-door hybrid called the Karma.

"The styling was substandard compared to what he unveiled for his product," says Tesla chairman Elon Musk. "He gave us an inferior work product, and it's obvious why."

Musk says that the Tesla designers have been working with Lotus to design the behind-schedule White Star in-house.

Fisker is yet to comment on the allegations.

Whatever the outcome of this knotty little battle, it's clear that the eco-conscious world of green car building isn't as altruistic as you might expect.