During the early days of the Indy 500 what did the cars include?

During the early days of the Indy 500, nearly all the cars were two-seat affairs that included a driver and an onboard “riding mechanic.” While the wheelman negotiated the track’s four treacherous turns, the mechanic monitored gauges and tire wear, made on-the-fly repairs and served as a traffic spotter. They sometimes even massaged the driver’s aching arms and neck as the race wore on. Riding mechanics were mandatory at the Indy 500 from 1912 to 1922 and 1930 to 1937, but teams later abandoned two-man cars after World War II to cut down on weight and improve aerodynamics.