Jim Clark won the 1965 Indianapolis 500, but found himself with a contentious second-place finish once again the following year. Eleven starters were eliminated in a first-lap accident during the 50th running of the race on May 30, 1966, which saw the fewest number of finishers (seven) in history.

That wasn't the only oddity in the race. Jim Clark spun on two separate occasions, neither of which involved contact. Although he pitted each time to allow the crew to inspect for damage, because he also refueled during those stops, he lost little track time. What his Lotus team failed to notice was rookie Graham Hill completing another lap.

Jackie Stewart inherited the lead when Lloyd Ruby pitted with engine trouble on Lap 147. Clark trailed his fellow Scotsman.

Controversy arose later because of a mix-up when Clark's teammate, Al Unser, crashed in Turn 4 on Lap 161. Officials announced it was Clark who crashed, so he wasn't scored that lap, according to the Indianapolis 500 Chronicle by Rick Popely. The confusion was compounded by frequent changes on the scoring pylon that sometimes indicated Clark was a lap ahead of Hill.

A different, less plausible, theory suggests that one of Unser's early laps was credited to Clark, and when scoring was reconciled later in the race, it and an additional lap were deleted from Clark's record.

Late in the race, Stewart led by a lap in his Lola T90-Ford, owned by John Mecom. On Lap 192 he lost oil pressure due to a broken scavenge pump that returned oil to the crankcase, forfeiting the lead to his teammate and fellow rookie Hill, 41 seconds ahead of Clark.

Believing Hill to be a lap down, Andy Granatelli, part-owner of Clark's STP Lotus, argued the win. The Tuscaloosa News quoted Granatelli: "It's impossible for Hill to be the winner. We were a lap ahead of Stewart and Hill was even farther behind. There's been an error."

Even Hill reportedly expressed surprise at winning because he hadn't passed a car on the track all day. Nevertheless, the IMS Radio Network, scoring the race independently, also proclaimed Hill the winner.

Once again, the Lotus team declined to file a formal protest, leaving Hill to become the first rookie to win since 1927.

Contested 500s — the 1911 race

Contested 500s — the 1963 race

Contested 500s — the 1981 race

Contested 500s — the 2002 race