Ray Harroun drove the Marmon Wasp to victory in the inaugural Indy 500. His car was the only single-seater—and thus the most aerodynamically advanced vehicle—in the field; every other driver had a riding mechanic to act as spotter. "Virtually everything else that ran was a stripped-down passenger car," explains Donald Davidson, Indianapolis Motor Speedway historian. "[Harroun's] car was built from the ground up as a competition car."
Louis and Arthur Chevrolet designed and engineered their brother Gaston's winning Monroe-Frontenac, which helped launch the trend toward streamlining. The vehicles that ran at Indy were strictly two-seaters until 1923, and the sanctioning body did away with them altogether in '37. Single-seaters were more aerodynamic, plus, by reducing the number of men on the track, organizers cut down on the probability of casualties.
Floyd Roberts set a qualifying record in this sturdy, rear-drive Burd Piston Ring Special, a Wetteroth-Miller, and on race day led 92 laps on his way to victory. Most passenger cars of the era were rear-drive, and while some front-drive cars were built especially to run at Indianapolis (the only track on the circuit at the time with a paved surface), the versatile rear-drive cars could run on dirt as well.