But Toyota executives said the fire, which occurred during a private test run at Fuji International Speedway, was unrelated to the car’s adoption of hydrogen fuel instead of gasoline. The cause, the company said, was a pipe joint loosened by vehicle vibration. “What I want everyone to understand today is that hydrogen was not the cause of this problem,” Tomoya Takahashi, president of Toyota’s Gazoo Racing Company, said at a briefing. “Rather, it is as the insufficient consideration of our design work,” he said. “Whatever fuel we used could have leaked and caught fire.” Despite the setback, Toyoda himself ordered…