Five of the greatest innovations from the Indianapolis 500

The field at the first and 99th runnings of the Indianapolis 500 in 1911 (L) and 2015 (R) respectively.

For most of the last century, the Indianapolis 500 was a hotbed of automotive innovation, where race-car designers and builders pulled out all the stops to win at the fabled Brickyard.

Sadly, like in most forms of motorsports, the rules box is might tighter at Indy than it used to be. Still, there have been plenty of interesting developments that came about because of this race. Here are five big innovations introduced at the Brickyard over the years.

Jack Brabham finished in ninth position in his Cooper Climax at the 1961 Indianapolis 500.

REAR-ENGINED CARS – Up until the mid-1960s, front-engined cars dominated at Indy, with big roadsters ruling the roost in the 1950s and ‘60s. Jack Brabham ran a funny-looking rear-engined car at Indy for the first time in 1961 and, just four years later, Jim Clark put one of Colin Chapman’s Lotus racers in victory lane. By 1970, the roadsters were gone forever.

“The independent suspension was the key, not the fact that the engine was in the back,” said three-time champion Johnny Rutherford. “… The independent suspension compared to the straight axle of the roadster just made it stick to the track so much better.”

Filtered image of Parnelli Jones driving the No. 40 STP gas turbine car through Turn 1 as part of Andy Granatelli’s racing efforts.

TURBINE CARS – Andy Granatelli and his Day-Glo Orange STP cars were always a sight to behold but, in 1967, he brought his masterpiece to Indy: A race car powered by a huge helicopter turbine engine. Parnelli Jones dominated the ’67 500, but a $6 transmission bearing failed with four laps to go, costing him the race.

The following year, Joe Leonard was leading in another Granatelli turbine when his car broke on Lap 191, putting him out of the race. After that, the turbines were banned.

“It dominated Indy,” two-time winner Emerson Fittipaldi said. “A very advanced car with a helicopter turbine – it was a spectacular car. It dominated so much it was banned.”

Al Unser Jr. races en route to victory at the 1994 Indianapolis 500.

MERCEDES LOOPHOLE – Using a little-known loophole in the rules, Roger Penske showed up at the 1994 Indy 500 with a secretly developed pushrod Mercedes engine that made more than 1,000 horsepower, roughly a 20 percent power advantage over his competitors.

Penske drivers Al Unser Jr. and Emerson Fittipaldi qualified 1-2 and, on race day, Fittipaldi dominated, leading 145 laps and putting the entire field at least one lap down. But he crashed late in the race, handing the victory to Unser Jr.

Johnny Rutherford prepares to make an exhibition lap in his 1980 winning Jim Hall Chaparral before the 2010 Indianapolis 500.

GROUND EFFECTS – In the late 1970s, Colin Chapman and Team Lotus led the ground effects revolution in Formula One, basically shaping the bottoms of the sidepods of his Lotus 79 like upside down airplane wings and using side skirts to seal off airflow beneath the car. The combination generated tremendous aerodynamic downforce, pushing the cars into the track. Mario Andretti won the 1978 Formula One title in a Lotus 79.

Two years later, American race car builder Jim Hall, who had preceded Chapman with ground effects in the late 1960s, built one of the most dominant Indy winners ever, the Chaparral 2K, which he first ran in 1979 but perfected in 1980. In the ’80 500, Johnny Rutherford qualified the 2K on the pole, led 118 laps and won by nearly 30 seconds. Rutherford would go on to take the series championship that year as well.

Milka Duno crashes out of the 2007 Indianapolis 500.

SAFETY – Over its long history, the Indy 500 has been a place where safety innovations have continuously come into play, often translating from race cars to passenger cars in the process. And today’s racers can be thankful for the energy-absorbing SAFER barriers, which were first installed at Indianapolis in May 2002.

“If you look at all the innovations at the Indy 500, the No. 1 greatest is safety,” said 1996 champion Buddy Lazier. “You can argue everything from seatbelts to disc brakes filtered down to the auto industry and now, every single American car enjoys them.”

The Associated Press contributed to this story.