Le Mans, France - Toyota believes a thumbs-up gesture of support by another team's driver on pit lane cost it a first 24 Hours of Le Mans victory at the weekend.
"You couldn't make this up," said a team spokesman after video footage circulated online of the incident late on Saturday night.
The images showed French driver Vincent Capillaire, helmeted and about to change shifts, running across to the leading Toyota as it waited for a red light to change at the pit lane exit.
Capillaire gave Toyota driver Kamui Kobayashi a thumbs-up sign, which the Japanese interpreted as a signal to go despite the light still being red.
"Drivers are told you must at all times follow the marshals," said the Toyota spokesman, who explained that Kobayashi had mistaken Capillaire for one of the officials who also wear helmets and overalls on pit lane. With the team shouting at him to stop and not go out on track, Kobayashi stopped and started the car several times in the confusion. In the process, he burned out the car's clutch which led to retirement shortly afterwards.
"It would not have happened without that stop-start, said the spokesman. "He put more stress on the clutch than it would normally have encountered and destroyed it. I don't think he (Capillaire) did it on purpose but it triggered a chain of events."
The Frenchman, who was part of the second tier Algarve Pro Racing LMP2 team, gave his version of events on his Facebook page.
"I wanted to show my encouragement to the leader car, stopped at red light a few metres in front of my box," he said. "It was a spontaneous encouragement mark as it happens between pilots. I was fined by stewards for this gesture and I admit it was inopportune. I regret that."
Porsche ultimately won the race with its second car that had spent well over an hour in the garage for repairs and rejoined on Saturday some 22 laps behind Kobayashi.
Toyota had another car retire after a collision while its third TS050 hybrid came home eighth after a long period in the garage with mechanics working on the front motor and battery.
Only one Japanese manufacturer has ever won Le Mans, Mazda in 1991. Toyota has been five times runner-up and has spent hundreds of millions of dollars over the years in pursuit of victory at the French endurance classic.