Owners of Tesla Motors electric vehicles in Norway have filed a lawsuit against the company, claiming that the Insane Mode of the cars does not go fast enough.

The Norwegian customers, numbering around 126, are seeking refunds from the U.S.-based electric car manufacturer because their Model S P85D vehicles reach only 469 horsepower, compared with the marketed figure of 700 horsepower that Insane Mode is said to provide.

The horsepower of the Model S P85D is too low, said Wikborg Rein law firm attorney Kaspar N. Thommessen, who is representing the plaintiffs. With lower horsepower than marketed, the performance of the car is affected, the customers claimed.

"The consumers seek compensation for the lack of performance," Thommessen stated in an e-mail, with the hearing for the case scheduled at the Oslo City Court this coming December.

The Model S enjoyed significant success in Norway, partly due to state subsidies that encouraged customers to purchase electric vehicles. The Model S P85D variant is no longer being sold by Tesla Motors in the country, as sales have shifted to the Model S P90D, which is its successor.

Insane Mode was introduced by Tesla Motors with the Model P85D, with the acceleration option promising the aforementioned 700 horsepower to allow the electric vehicle to go from zero to 100 kilometers (62 miles) per hour in around 3.1 seconds to 3.3 seconds.

Tesla Motors has rejected the claims made by its customers in Norway and the accompanying lawsuit. In an e-mail, the company confirmed that through its own testing and studies made by third-parties, the Model S P85D is capable of reaching the horsepower and speed that is promised by the Insane Mode. As such, the car is able to meet the requirements according to the method of measurement that authorities have required, stated Tesla Motors spokesperson Even Sandvold Roland.

Drag Times, a drag-racing website, had fun with Insane Mode in January of last year, as documented by a popular video that showed the shocked reactions of passengers as the driver pressed the Insane Mode button on the Model S P85D. The burst of speed that going into Insane Mode provides unsurprisingly caused the passengers to freak out.

Insane Mode in Tesla Motors vehicles, however, has long been overshadowed by the more powerful Ludicrous Mode, which was introduced with the launch of the Model S P90D. With the new acceleration option, the time needed for the electric car to go from zero to 100 kilometers per hour was further reduced to 2.8 seconds.