Original: In fact , Formula One in its early years was so expensive and entrants were so few that in 1952 and 1953 all World Championship Grand Prix races were run in Formula Two ( although non-championship F1 events continued to be held - the Indianapolis 500 was part of the World Championship between 1950 and 1960 but ran to its own regulations and was never formally a Formula One race ) .
Simplified: Formula One in its early years was very expensive . There were so few cars entered for the 1952 and 1953 that the World Championship Grand Prix races were run to Formula Two rules .