Le Mans, 1966.
Ken Miles/Hulme driving the Ford GT, in which they won… except they didn’t.
It’s a long story, but basically Miles/Hulme have fought an epic battle with Amon/Mclaren for the lead in this Le Mans series. The Ford GT proved to be greater and they won the event only by a few dozen meters.
However, someone remembered to read the Le Mans rules to such an extent that they’ve found out that the winner car is the one which has travelled a longer distance — from its very starting point. Since Amon & McLaren had started further back on the grid, they were later considered the winners of the 1966 Le Mans.
Ken Miles has never forgiven Ford or Carrol Shelby for this mistake, since they were the ones who ordered them to slow down near the finish to close the gap.