In the movie Ford v Ferrari, it is suggested that Ken Miles was told to slow down in order to ensure that Carroll Shelby would win the 24 Hours of Le Mans. While this may be true, there is no evidence to support this claim.
It is believed by many that Ken Miles was one of the greatest racing drivers of all time. He was a master at setting lap records and winning races. In 1966, he set the fastest lap time ever at the 24 Hours of Le Mans race in a Ford GT40 Mark II. He also won the 24 Hours of Daytona and 12 Hours of Sebring in 1967. So, it seems unlikely that he would have been ordered to slow down in order to let another driver win.
There are several theories as to why Ken Miles may have slowed down during the last few laps of the 1966 24 Hours of Le Mans race. One theory is that his car was running low on fuel and he didn't want to risk running out before crossing the finish line. Another possibility is that his tires were wearing thin and he didn't want to risk a blowout at high speeds. Whatever the reason, we may never know for sure what happened during those last few laps of the race.