An ex-Formula One driver is suing a motoring journalist after his classic racing car's engine blew up during a test drive, telling the High Court: "if you bend it, you mend it".
David Piper allowed Mark Hales, an experienced racing driver and freelance writer, to take his treasured Porsche 917 for a spin on a test track for a magazine article.
But disaster struck when the engine on the green-and-white vintage motor - valued at £1.25m - failed catastrophically as Mr Hales drove it around the course.
Mr Piper claims the damage was caused by Mr Hales failing to engage the right gear and "over-revving" the engine and wants him to pay for the repairs the car needed.
He told London's High Court: "If you bend it, you mend it."
The 82-year-old, of London Road, Windlesham, Surrey, is seeking around £50,000 for the cost of fixing the engine, which had to be shipped to Germany for specialist repair and the "loss of use" he endured while the car was out of action.
Mr Hales, 62, of Fen Lane, Conisholme, Lincolnshire, denies any liability to pay and contends that a "mechanical failure" caused the car to slip out of gear.
The court heard Mr Hales drove the Porsche around a track at Cadwell Park, near Louth, Linconshire, in April 2009 so he could write an article for Auto Italia magazine comparing the car with another classic motor from the same era - a Ferrari 512S.
Mr Hales has an extensive track record of racing cars and has won around 150 races during his 30 years' experience of driving as both an amateur and professional.
He paid Mr Piper a "bail fee" of £2,000 to use the 917 and took it around the course several times without incident.
But, as he completed a lap of the track, the engine blew up - causing devastating damage which cost nearly £40,000 to repair.
The iconic car, which was sold by Mr Piper in July last year, was repaired by a Porsche specialist and continues to be driven in classic races.
Mr Piper's lawyers told Judge Simon Brown QC it was agreed that the damage was caused by the over-revving of the engine to 8,200rpm, and that Mr Hales was 'expressly warned' to ensure the revs did not exceed 7,000rpm.
His barrister, Alexander Wright, said: "The central factual dispute is not over the mechanical cause of the damage, but as to why the engine over revved as it did.
"There are two competing theories - the claimant's case is that the defendant, despite the very clear instructions given, failed to engage gear. He missed gear going into third causing the engine to over-rev and leading to damage.
"The defendants say there was an inherent and pre-existing mechanical fault in the gear box so that the gears didn't properly lock and engage and slipped out of gear."
When quizzed by Mr Hales' lawyers about the possibility of a fault with the car's gearbox, Mr Piper denied there was any problem.
He said: "If there was any question of a gearbox problem, I would have asked him to stop and not drive any more."
During his 15 years of motor racing, from 1955 to 1970, Mr Piper's successes included seven wins out of nine in the Nine Hour Endurance Race at Kyalami, South Africa, and he took part in three Formula One World Championship Grands Prix.
He also drove cars for the Ferrari, Ford and Porsche factories and owns another Porsche 917 which he has had since 1969.
The 917 was created in response to a rule change in endurance racing and gave the German car firm its first overall wins in the legendary 24-hour Le Mans race in the early 1970s.
Known for its high speeds and enormous power outputs, a 917 was featured in the 1971 Steve McQueen film, Le Mans - during the filming of which Mr Piper suffered an accident that cut short his professional racing career.
The hearing continues.