Race Weekend Central

Inside IndyCar: Aero Kits

With the NTT IndyCar Series’ next on-track excursion coming at Texas Motor Speedway on Sunday, April 2, what better time to get familiar with the differences between IndyCar machinery on ovals vs. road courses?

Unlike Formula 1, IndyCar teams are not free to develop the aerodynamic parts of their chassis. Instead, each team competes at each race using a universal aero kit – that is to say, all aerodynamic parts of each car are manufactured to identical specifications. Previously, from 2015 to 2017, Chevrolet and Honda each used their own respective aero kits designed around the DW12 chassis.

In 2023 we are living in an era of acceptable coexistence with the universal aero kit, but the start of this relationship was rather difficult to swallow.

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From 2015 to 2017, IndyCar oval racing in particular was a sight to behold. The high downforce, aero-disruptive nature of the cars meant that the draft on ovals was extremely powerful, creating a period of consistent pack racing that has seldom been seen in the history of the series.

During this period, three of the five most competitive Indy 500s took place. The 2016 race saw 54 lead changes, 2015 featured 37 swaps of the top position and the 2017 running produced 35 of its own. To make matters more unbelievable, the 2015 MavTV 500 at Auto Club Speedway – one of the most hotly contested races in IndyCar history – featured 3,173 on-track passes, 2,537 of them being for position. These 3,173 passes constituted over half of all passes for position in the 2015 IndyCar season.

Moreover, bringing aerodynamic components of the cars to a spec standard brought parity throughout the already tight IndyCar field even closer, preventing dominance by one manufacturer the like of which was seen from Chevrolet in 2015.

Back to the point, competitive races with ample amounts of passing are, of course, not bad. However, pack racing on ovals in open-wheel cars at speeds of over 210 mph is somewhat questionable. Contact between open-wheel cars at speed can be disastrous compared to stock cars, and a series of major crashes in the early-to-mid 2010s had safety on everybody’s mind.

Chiefly, how can cars still pick up a slipstream, but no longer be aerodynamically incentivized to run nose-to-tail lap after lap?


On the surface, the answer was to streamline the cars extensively.

Deeper down, the answer was… to streamline the cars extensively. To criminally oversimplify the matter, IndyCar’s solution worked too well.

Compared to the previous generation of the DW12, the universal aero kits looked rather minimalist on reveal.

For all intents and purposes, the entire rear end of the car was scrapped. Large, broad rear wings and wheel guards were dropped in favor of a minimal, sleek rear wing that resembled a B-2 stealth bomber more than any recent IndyCar design. On the front end of the equation, the motif of large front wings on road courses and smaller front wings on ovals was maintained.

This newer design focused on producing downforce through the underside of the car, reducing the amount of dirty air produced. Theoretically, this makes the air behind the car cleaner, allowing competitors to follow more closely through corners. In reality, passing at oval courses in particular became harder.

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The 2018 Indy 500 featured an underwhelming 30 lead changes. Comparatively, this was atrocious in the context of the 2010s. However, this still puts the 2018 race as the ninth most competitive 500 in history. Ahead of the race, multiple drivers confirmed that the feeling of following another car was more tedious than in previous years.

The drivers were correct, oval races in 2018 proved to be very track position-centric events. This fact reared its ugly head in that year’s ABC Supply 500 at Pocono.

With passing made much more difficult and track position at a premium, many drivers knew that their best chance to gain positions was on starts and restarts, when the field was bunched together and not quite up to speed.

Then-rookie Robert Wickens made a blitz of a start and set himself up for a run on Ryan Hunter-Reay into Pocono’s famous Tunnel Turn. Unable to keep his car planted to the bottom of the track through the corner, Wickens drifted up the track into Hunter-Reay, with disastrous results.

As time went on, the bugs of the kit were sorted out and competitiveness at the 500 ascended to its pre-2018 levels. The 2021 running saw 35 lead changes, while 2022 featured 38. At Texas, the situation is likewise more competitive, though the pack-style racing last seen in 2017 has yet to reappear.

On road courses, the general idea of the aero kit remained intact. Large, angular front wings and bulky rear wings remained the standard. For short ovals such as Phoenix and Gateway a slightly reduced front wing was adopted.

Next Up?

Currently, there is no set date for the unveiling and implementation of the next IndyCar chassis.

With a new hybrid engine package coming to the series in 2024, the plans for the next generation of IndyCar machinery are most certainly already being deliberated. With one of the most competitive on-track products across all of motorsport, time will tell what comes next for the series.

All this being said, nothing outwardly suggests that there are any fundamental changes to the structure or function of the cars coming in the foreseeable future. Though the universal aero kit and its style of racing took many of us by surprise, I would wager that fans aren’t in any hurry to see this generation of cars done away with.

About the author

Alex is the IndyCar Content Director at Frontstretch, having initially joined as an entry-level contributor in 2021. He also serves as Managing Director of The Asia Cable, a publication focused on the international affairs and politics of the Asia-Pacific region which he co-founded in 2023. With previous experience in China, Japan and Poland, Alex is particularly passionate about the international realm of motorsport and the politics that make the wheels turn - literally - behind the scenes.

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