Tesla denied Friday putting pressure on customers to stay quiet over problems in its luxury all-electric cars amid questions about the strength of the suspensions in the popular Model S.

In a sign of new differences between the upstart Silicon Valley automaker and the US car safety regulator, the National Highway Traffic Safety Administration raised questions about a "troublesome nondisclosure agreement" the company asks customers to sign for repairs.

In a post on its website, Tesla acknowledged presenting a "Goodwill Agreement" to customers given free or discounted repairs.

In it the customer agrees "to keep confidential our provision of the Goodwill, the terms of this agreement and the incidents or claims leading or related to our provision of the Goodwill."

But Tesla said it was to protect itself legally rather than quieting Tesla owners.

"Tesla has never and would never ask a customer to sign a document to prevent them from talking to NHTSA or any other government agency. That is preposterous," it said.

"The basic point is to ensure that Tesla doesn't do a good deed, only to have that used against us in court for further gain."

Even so, the company said it would work with NHTSA on the issue "to see if we can handle it differently."

The problem arose after a customer complained of suspension failures on his Model S, a luxury sedan with a base price of $70,000, and after a popular auto website, Daily Kanban, said the case was not an isolated incident.

Tesla denied there was any general problem, saying the specific car in question was owned by someone who "lives down such a long dirt road that it required two tow trucks to retrieve the car."

"There is no safety defect with the suspensions in either the Model S or Model X," it insisted.

It also said the NHTSA had asked for and been provided information on the issue but had not opened any formal probe.

Tesla, which has plans to expand from a niche car maker to a major player in the industry producing 500,000 cars a year by 2018, has been particularly sensitive to reports of problems with its cars, which can cost up to $150,000.

Bristling over an NHTSA recall order for a charging adapter in January 2014, Tesla founder Elon Musk ridiculed the agency's process, noting the charger problem was simply addressed electronically via a software update.

"No Tesla vehicles are being physically recalled," he said. "The word 'recall' needs to be recalled."

Source: AFP