Innovations at the Indianapolis 500

Ray Harroun, a retired engineer for Marmon, introduced the rearview mirror to a mass audience while winning the first-ever Indianapolis 500 on May 30, 1911, in a Marmon Wasp.

In 1908, Popular Mechanics first detailed how police used a reflector on their vehicle's dash much like how one would use a rearview mirror.

However, Harroun is given credit for advancing the commercialization of the rearview mirror.

Harroun's was the only car in the 1911 race not to have a riding mechanic onboard -- he mounted a 3-by-8-inch mirror on the hood instead.

He came up with the idea for the mirror after seeing something similar on a horse-drawn taxi when he was a chauffeur in Chicago. 

In 1922, driver Barney Oldfield ordered a safety harness for his car that was developed by a parachute maker. Before the 1922 race, there wasn't much holding a driver back when there was a crash. Front seat belts became mandatory in U.S. vehicles in the early 1960s.

Duesenberg was the first automaker to offer four-wheel hydraulic brakes in a car, according to Lou Phillips' book Cars. Duesenberg's innovation came three years before any other U.S. car offered them.

The technology was also found on the track.

The 1921 Indianapolis 500 was the first to have a car with four-wheel hydraulic brakes. The first cars with four-wheel disc brakes appeared on noted racing engineer Harry Miller's specials in the 1930s. They were developed by Miller.

First seen at the 1924 race, the new configuration lowered the car's center of gravity and cut weight. The transverse-mounted transmission eliminated the rear differential and driver shaft. The first Indianapolis 500 win for a fwd car would come in 1930.

Designed by racing engineer Harry Miller, the system combined front- and rear-wheel drive with a hydraulic clutch. Miller was convinced the configuration would provide better traction, especially around the Speedway's slightly banked curves. All-wheel-drive cars debuted in the 1932 race.

In 1923, Mercedes was the first to enter a super-charged car in the race.

One year later, Joe Boyer was behind the wheel of a Duesenberg -- the first American-built car designed with a supercharger. By 1926, every car in the field of 28 was supercharged.

Almost 30 years later, the 1952 Indianapolis 500 was the first race to feature turbocharged engines.

The #28 Cummins Diesel Special had a side-lying engine design and was the first Indy car to be tested in a wind tunnel for aerodynamics.

The car managed to start the race from the pole but didn't finish -- the turbocharger inlet became clogged with rubber debris.

While most production vehicles are not capable of hitting speeds that their Indy car counterparts hit at the Brickyard, airflow and down force is an important cog in vehicle development as fuel economy rules tighten. Design features such as wings and spoilers, which became the norm in the late 1960s and became legal in the early 1970s at the Brickyard, can make a big difference in terms of airflow on the racetrack and the morning commute.