In the aftermath of victory by Ray Harroun in the single-seat Marmon "Wasp" in the first 500-Mile Race the year before, new rules made the presence of riding mechanics mandatory; maximum engine size remained 600 cubic inches (9.83 liters) displacement.

With the car's momentum carrying it around to the fourth turn, DePalma and riding mechanic Rupert Jeffkins then entered themselves into motor racing lore, as well as inspired the cheers of the more than 80,000 in attendance, as they climbed from the vehicle and begin pushing it down the five-eighths of a mile main stretch toward the start-finish line.

Throughout the remainder of the field, only the top ten finishers earned prize money, rules stipulating all entries complete the 500 miles (800 km) to collect.

Ralph Mulford, being forced to stop numerous times due to clutch problems in his Knox, found irritation with the requirement and proceeded to drive on, long after all others were presented the chequered flag...and even after Speedway president Carl Fisher and starter Fred Wagner left the grounds (the latter after getting into an argument over whether to flag Mulford off before he had completed the distance, Wagner in favor and Fisher against).

Through numerous accounts of the run, including his reportedly changing shock absorbers for a gentler ride, as well as stopping for a dinner-on-the-go of fried chicken and ice-cream with his riding mechanic, Mulford's finish finally arrived, amid deserted grandstands and a setting sun over the main straightaway, 8 hours and 53 minutes after the start (approximately 6:53 p.m. local time), and with an average speed of 56.285 mph (90.582 km/h), which remains a record: the slowest finishing speed to date in 500 history.