In 1963, he raced in his first Indianapolis 500 and finished in second position behind Parnelli Jones and won Rookie of the Year honours. The 1963 Indy 500 result remains controversial. Before the race United States Auto Club (USAC) officials had told the drivers that they would black flag any car that was seen to be leaking oil onto the track. Late in the race, Jones' front-engined roadster developed a crack in the oil tank and began to leak oil. With the track surface already being slippery this resulted in a number of cars spinning and led to popular driver Eddie Sachs crashing into the outside wall. USAC officials were set to black flag Jones after the Sachs crash until his car owner J. C. Agajanian ran down pit lane and somehow convinced them that the oil leak was below the level of a known crack and would not leak any further. Colin Chapman later accused USAC officials of being biased because Clark and Lotus were a British team with a rear-engine car. Many, including journalist and author Brock Yates, believed that had it been an American driver and car in second place instead of Clark in the British built Lotus, officials would have black flagged Jones. Despite this neither Lotus nor their engine supplier Ford protested the result, reasoning that winning as a result of a disqualification when Jones had led for 167 of the races 200 laps (Clark led for 28 laps) and had set the lap record speed of on lap 114, would not be well received by the public.