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.
Front-drive cars like Mauri Rose's Blue Crown Spark Plug Special, a Deidt-Offy, were at an advantage because they had a lower center of gravity and were built especially to handle the bricks and asphalt at Indianapolis, which became slippery with oil. "It was quite an investment because the other tracks that were being used at the time, that car wouldn't work very well on," says Davidson. "You could only use it once a year."
Cockpits in cars like Bill Vukovich's Fuel Injection Engineering Special, an Offy, were slightly offset to the right—though not as much as Vukovich would lead us to believe in this photo—for lefthand turns at Indy and other oval tracks. About a decade later, as road courses became a part of the championship series, these cars were phased out in favor of vehicles that could run at all tracks.
A rear-engined car had run at Indy as early as 1939, but Jim Clark's Lotus-Ford was the first to take the checkered flag. Though sneered at by traditionalists who favored the front-engined roadster design, these vehicles, with their Grand Prix heritage, were far more nimble in the turns. "The balance was better so they could corner easier," says Davidson. By '69, every driver in the Indy field was behind the wheel of a rear-engined car.
Beginning in 1972, cars were allowed bolt-on rear wings, which increased downforce, or the vehicles' ability to hug the track. The front wings, which had started to appear in the late '60s, also helped. This was the era of the Eagle chassis. Gordon Johncock's Eagle-Offy was one of 19 in the field of 33 cars that year; the American-made Eagles would make up 52% of all cars that ran at Indy from '73 through '76.
Johnny Rutherford's Chaparral-Cosworth, also known as the Yellow Submarine, was one of 15 ground-effects cars in the race. The faster these cars went, the closer their rubber undersides would sit to the track, creating a vacuum that essentially sucked the car to the pavement. As Rutherford said of his '80 vehicle, "This car handles so well, I could probably take my hands off the steering wheel going down the backstretch."
Toward the end of the century, the cars became increasingly streamlined, as evidenced by Jacques Villeneuve's needle-nosed Reynard-Ford. He had an airbox above his head, a feature now included on all cars to provide air to the engine and increase power. On this particular model the winglets on the side are angled down in an attempt to achieve greater downforce. "It looks like they were bent," says Davidson, "but they were designed like that."
The so-called "third-generation" of IndyCar, introduced after a year of tests, had a reduced weight, with slightly wider sidepods on the driver's right and left, and was held to higher crash standards in an effort to improve driver safety. Tony Kanaan drove his Dallara-Honda to a third-place finish in 2003 and was runner-up the following year.
Meet the new car—not the same as the old cars. The Italian firm Dallara created the new DW12 chassis, named for the late Dan Wheldon, who helped test the car before his fatal accident at Las Vegas Motor Speedway last fall. The premium in the new design is on driver safety—particularly on preventing cars from going airborne, as Wheldon's did. Recalls driver Tony Kanaan of his first peek at his new ride, "It looked like the Batmobile. I was like, Is this an IndyCar or a superhero car?"
[The following text appears within a diagram. Please see hardcopy or PDF for actual diagram.]
Larger drivers' compartments mean easier postcrash extraction—and greater comfort. Says Kanaan, "I can turn the steering wheel left and right without touching the side of the tub, which I couldn't do before."
The compartments on either side of the driver extend farther over the wheels. Cars racing side-by-side would be likelier to trade paint than to brush wheels—and thus likelier to stay on the track.
These protrude approximately 12 inches above the side panels in an effort to prevent the wheels from rolling up into the sidepod and smashing dangerously close to the driver's safety cell.
The engines, by Honda, Chevrolet and Lotus, are at most 2.2 liters (down from 3.5). But they are also turbocharged for the first time since 1996 and are more efficient than ever, producing from 550 to 700 horsepower.
The body extends over the front of the rear tires, to avoid wheel-to-wheel contact, since, as IndyCar vice president of technology Will Phillips points out, "You're never going to get rid of one car hitting another."
ENERGY ABSORPTION FOAM
There are three inches of foam behind the driver's back seat and three-quarters of an inch under the seat. The sides of the chassis are also designed to withstand a far greater impact.
IndyCar wanted to limit wheel-to-wheel contact (which can make cars take flight), and these bumpers behind the back wheels are aimed at doing just that.
*RACE AVERAGE. ALL OTHERS, QUALIFYING SPEED
ROBERT LABERGE/GETTY IMAGES (REAR)