(Inside Science) -- In the inaugural Indianapolis 500 race in 1911, driver Ray Harroun included an innovative piece of technology in his car.
As the only solo driver in the race, he lacked a companion to watch out for vehicles closing on him from the rear. So he jury-rigged the first ever rearview mirror.
Harroun won the race, but without help from his innovative mirror. It vibrated so strongly that he couldn't see anything in it.
Nevertheless, the rearview mirror became an essential part of everyday driving, just as so many other advances have moved from the track to the highway.
In the 98 runs since then, technical improvements devised for IndyCars and other racing autos have continued to influence the vehicles that appear in your neighborhood car dealerships.
"A lot more technology than you would think makes the transition from the racetrack to the road," said Diandra Leslie-Pelecky, a physicist and author of "The Physics of NASCAR."
"New technology goes pretty quickly into regular cars," said Danny White, director of motorsports at Purdue University in West Lafayette, Indiana. "Automobile people are very comfortable taking changes devised for racing cars into consumer autos."
So when the 100th Indianapolis 500 takes place on Sunday, canny viewers will be checking on the new technological twists that might feature in what the trade calls "road cars" in a few years.
The IndyCar series and other forms of racing provide a test bed for automakers, oil companies, tire manufacturers, and others to test new technologies. The harsh conditions of racing give car parts, fluids, and ancillary equipment the types of scrutiny they need to convince manufacturers of their suitability for passenger vehicles.
"It's easier to check the value of new developments in a low-volume racing environment first before introducing them into high-end road cars," said Tino Belli, director of aerodynamic development for IndyCar, the sport's sanctioning body.
A lot of the technology that moves from track to road involves safety.
"If something is going to work at more than 100 miles per hour on a racetrack, it's probably going to work at 70 miles per hour," Leslie-Pelecky explained.
Familiar safety features that have moved from race cars to consumer cars include seat belts, impact systems and fire suppression.
"All have improved considerably over the past ten years," White pointed out.
On the track, "the steel and foam energy reduction, or SAFER, barrier was revolutionary," Leslie-Pelecky recalled. These barriers, placed around the track, flex when struck by a car. That reduces the amount of impact energy that transfers directly to the driver.
IndyCar engineers helped to develop the technology in 1999 and used it for the Indianapolis 500 three years later. In 2010, it was installed on a road course in Watkins Glen, New York. Since then, it has begun to move onto regular highways.
Tire technology has also seen particular improvement in recent years thanks to Indy testing. "Nitrogen-filled tires came from the racing series; every time you get a new set of tires, you can get nitrogen," White said. The gas stabilizes tire pressure.
Another issue high on the list of automakers' concerns is fuel efficiency. The replacement of steel components with lighter-weight plastics and composites for dashboards and other internal systems started with race cars.
"Aluminum was the material of choice in racing back in the 1950s; they appeared in road cars only in about 2010," Belli said. "And carbon fiber was pioneered on a McLaren race car in the early 1980s but has only recently appeared on fairly high-end road cars."
Some automakers set out to design race cars with the immediate goal of transitioning their technology to the road.
Three years ago, the IZOD IndyCar Series changed the requirements for its cars to twin-turbocharged V6 engines run on ethanol. That persuaded Chevrolet to return to the series in order to test its smaller, turbo-powered engines for fuel-efficient road cars.
To get the best performance from those cars, Chevrolet needed off-the-shelf engine oil and other liquids. So instead of using oils blended specifically for racing, the automaker used lubricants from local auto supply stores during races.
Sneaking a peek at tomorrow's technology
What features found at Sunday's Indianapolis 500 can you expect to see when you look for your next auto?
Thin film coating on the exterior of cars looks a likely bet.
"Engine builders are extremely interested in cutting inefficiencies," Leslie-Pelecky said. "Thin films on a car body's surface reduce friction. They also dissipate heat build-up away from sensitive auto parts that could otherwise melt."
The coatings consist of expensive space-age materials such as diamond-like carbon and titanium nitride. But they cost relatively little because they are extremely thin – about a hair's breadth.
Inside today's IndyCars, drivers have significantly more control than the average auto commuter, such as over how quickly gas moves to the combustion chamber. "If they find the engine is running rich or lean, they can adjust it from inside their cars," said Leslie-Pelecky.
Another advance this year should reveal itself through the absence of drama.
"We've taken the study of aerodynamic instability to a new level this year, because last year a couple of cars went airborne in practice," Belli said. "Both Chevrolet and Honda have had to change their designs to show that they are aerodynamically stable as they spin."
And coming soon to a track near you: Races for driverless cars.
Starting in Fall, the Formula E Championship, which uses only electric-powered cars, will run a race for "autonomous cars" before each of its main events for cars with drivers.
Because of problems with blood flow to the human brain, White said, cars with drivers "are limited to top speeds of 230 – 235 miles per hour." Driverless autos have no such limit, and racing them at extraordinary speeds could popularize them with the general public.
"This is as big a transition in technology as in the turn of the 20th century, when race cars had a lot of impact on the change from horse and buggy to automobiles," White said.