What Is The Top Speed Of Indy 500 Cars?

Since the race's inception in 1911, the Indianapolis 500 — under the eponymous IndyCar discipline — boasts some of the highest average speeds in all of motor racing. What began life as a requirement to average over 75 miles an hour over each quarter-mile to qualify, became a 200-plus mile-per-hour jostling match of racecraft, slipstream strategy, and sheer nerve. IndyCars developed over a century to become highly specialized machines, and today's IndyCars are certainly fast. In fact, they are the fastest single-seater class, period; outpacing even an F1 car in a straight line (though not in the corners). However, they aren't actually the all-time fastest an IndyCar ever went in a straight shot.

For that, we have to reference qualifying, where only one car is on-track at any given time and positions are determined by a car's average speed across the oval. It was during such a run in 1996 that Arie Luyendyk set the absolute top-speed benchmark, reaching 237.498 miles an hour in one lap. Over the course of four laps, he set a combined pace of a blistering 236.986 mph. And finally, his vehicle went faster than any IndyCar had ever been — 239.260miles per hour, with the help of slipstream during a practice session. 

These days, most IndyCars hover around the 230 mark, with remarkably close speeds throughout the pack. In fact, the 2024 Indianapolis 500 marked the fastest qualifying speed at 234.220, set by Scott McLaughlin — and the slowest being Graham Rahal's 229.974, a difference of less than five miles an hour. Still, this begs the question: How on Earth do engineers get these cars to go that fast?

Under ideal conditions, a driver can theoretically race the entirety of the Indianapolis 500 without ever lifting off the throttle. Of course, racing is an extremely dynamic sport and this never really happens in reality — accidents occur, cars pull in front of others, and so on. In general, IndyCars reach the speeds they do because of a carefully-balanced relationship between three factors: horsepower, mechanical grip, and aerodynamic drag. 

The first is relatively easy enough — the more power you have, the faster you go. Modern IndyCars use either a Chevrolet or Honda-sponsored 2.2L hybrid V6 producing between 550-700 horsepower, though both engines were co-developed and are identical. Consequently, all IndyCar vehicles reach very similar power levels. As for aerodynamics, the idea is to get as low drag coefficient as possible within the allowed regulations. It's up to individual teams to trim aerodynamics to best suit the cars' levels of mechanical grip, defined as the grip provided by the tires adhering to the road surface. 

The higher the mechanical grip, the less aerodynamic drag is needed to keep a race car stuck to the road. And the less drag a car has, the faster it will go in a straight line for the same amount of power and weight. That's why speeds remain so similar throughout the entire field in the Indy 500: When all the cars have identical bodywork and engines according to the rulebook, with the only permitted aerodynamic changes being the angles on the wings and such, then teams will naturally gravitate towards an "optimal" balance. That balance creates an average of 231.943 miles per hour at Indianapolis qualifying sessions across the field, as of 2024.