The manufacturer said it had been working with the United States National Highway Traffic Safety  Authority for the last six months, aiming to recreate the conditions that led to a crash test damaged Volt catching fire in May. Last week, the NHTSA said it was investigating the Volt’s battery packs after a second damaged unit had begun smoking after a crash test.

In its statement, GM said no Volt had caught fire after an accident on public roads, and added that it was establishing a senior level engineering team to help eliminate concerns from motorists and establish protocols for handling battery packs after a crash.

Existing Volt owners will be offered a free loan vehicle until the investigation is complete.

Mark Reuss, president of GM North America, said: ‘The Volt is a five-star safety car.  Even though no customer has experienced in the real world what was identified in this latest testing of post-crash situations, we're taking critical steps to ensure customer satisfaction and safety.

‘Our customers' peace of mind is too important to us for there to be any concern or any worry. This technology should inspire confidence and pride, not raise any concern or doubt.’

Mary Barra, GM’s senior vice president of global product development, added: ‘GM and the agency's focus and research continue to be on the performance, handling, storage and disposal of batteries after a crash or other significant event,” she said.

‘We’re working with NHTSA so we all have an understanding about these risks and how they can be avoided in the future.  This isn’t just a Volt issue.  We’re already leading a joint electric vehicle activity with Society of Automotive Engineers and other automotive companies to address new issues, such as this protocol of depowering batteries after a severe crash.’