Mitsubishi Motors UK says it is investigating why a passenger airbag in an R-reg Shogun deployed while parked at a Bristol dealership.

A customer was about to get into the vehicle to go for a test drive when the airbag went off, throwing him from the Shogun.

Mitsubishi says it has sent one of the Shogun's electronic control units – a car's equivalent to an airliner's black box – for examination by MMC engineers in Japan.

A UK spokesman said: “The airbag fired because the customer forcefully pushed the passenger seat forward against the stops. The noise or force exerted was enough to set trigger the airbag. It obviously shouldn't have done and we're at a loss as to why. The ECU could be faulty.”

He stressed that the incident was a one-off and there is no evidence that the airbag was a replacement or had been tampered with.

“He thought he had been shot,” said Mark Williams, sales manager at Mitsubishi Motors Bristol, of the customer's reaction. The cost of repair was put at £2,800 – and the sale lost.