Centennial Era

In 2009, the Indianapolis Motor Speedway began a three-year long "Centennial Era" to celebrate the 100th anniversary of the opening of the track (1909), and the 100th anniversary of the first Indy 500 (1911).^[34] As a gesture to the nostalgic Centennial Era celebration (2009–2011), tickets for the 2009 race donned the monikor "93rd 500 Mile International Sweepstakes."^[35] It is the first time since 1980 that the "Sweepstakes" title has been used. During the month of May 2009, the ordinal (93rd) was used very sparingly, and for the first time since 1981, was not identified on the annual logo. Instead, in most instances in print, television, and radio, the race was referred to as the "2009 Indianapolis 500." Since the race was not held during WWI and WWII, the advertised Centennial Era will occur during the 93rd/94th/95th runnings. To avoid confusion between the 100th anniversary, and the actual number of times the race has been run, references to the ordinal during the Centennial Era are being curtailed.

[edit] European incursions

In the meantime, European manufacturers, gone from the Indianapolis 500 for nearly two decades, made a brief return just before World War II, with the competitive Maserati 8CM allowing Wilbur Shaw to become the first driver to win consecutively at Indianapolis in 1941.^[36] With the 500 having been a part of the Formula One World Drivers' Championship between 1950 and 1960,^[36][37] Ferrari made a discreet appearance at the 1952 event with Alberto Ascari,^[38] but European entries were few and far between during those days.

In fact, it was not until the Indianapolis 500 was removed from the Formula One calendar that European entries made their return, with Australian Jack Brabham driving his slightly modified F1 Cooper in the 1961 race.^[39] In 1963, technical innovator Colin Chapman brought his Team Lotus to Indianapolis for the first time, attracted by the large monetary prizes, far bigger than the usual at a European event. Racing a mid-engined car, Scotsman Jim Clark was second in his first attempt in 1963,^[40] dominating in 1964 until suffering suspension failure on lap 47, and completely dominating the race in 1965, a victory which also interrupted the success of the Offy, and offering the 4.2 litre Ford V8 its first success at the race.^[41] The following year, 1966, saw another British win, this time Graham Hill in a Lola-Ford.^[42]

Offenhauser too would join forces with a European maker, McLaren, obtaining three wins for the chassis, one with the Penske team in 1972 with driver Mark Donohue,^[43] and two for the McLaren works team in 1974^[44] and 1976 with Johnny Rutherford.^[45] This was also the last time the Offy would win a race, its competitiveness steadily decreasing until its final appearance in 1983. American drivers kept on filling the majority of entries at the Brickyard for the following years, but European technology had taken over. Starting in 1978, most chassis and engines were European, with the only American-based chassis to win during the CART era being the Wildcat and Galmer^[46] (which was actually built in Bicester, England) in 1982 and 1992 respectively. Ford and Chevrolet engines were built in the UK by Cosworth and Ilmor, respectively.