IndyCar returned to a single-chassis formula with the Dallara DW12 in 2012, following years of controversy over the CART–IRL split and the chassis competition of the previous era. The spec chassis was intended to reduce costs and simplify the technical landscape, but manufacturer partners Honda and Chevrolet pushed for a mechanism to differentiate their programmes beyond engine performance alone.
The aero kit programme was conceived as a compromise: the chassis tub, safety structures, and mechanical package would remain spec, but each manufacturer could supply its own bodywork — front wings, rear wings, sidepod configurations, and associated aerodynamic elements — designed around that common structure. This allowed for visual and aerodynamic distinction between Honda-powered and Chevrolet-powered cars without requiring teams to source different chassis.
The 2015 IndyCar season marked the debut of manufacturer aero kits, with the St. Petersburg street circuit season opener serving as the first competitive event for the new packages. Both Honda and Chevrolet presented dramatically different visual interpretations of the DW12 bodywork, with elaborate front wing assemblies and aggressive aerodynamic profiles that drew immediate comment for their complexity and fragility.
Concerns about part durability were validated immediately. At St. Petersburg, numerous front wing contact incidents damaged bodywork throughout the field, and teams found that replacement parts were scarce. The complexity and uniqueness of each manufacturer's components meant that a part damaged in an incident was difficult to replace quickly from available stock, creating logistical challenges for crew chiefs and strategists.
Despite operational difficulties, the aero kits era produced competitive racing. The 2015 season saw multiple different winners across its 16 rounds, with Scott Dixon taking the championship on a tiebreaker over Juan Pablo Montoya despite neither dominating the season outright. The Indianapolis 500 was won by Montoya, and the season was ultimately overshadowed by the death of Justin Wilson at Pocono Raceway in August, who sustained fatal head injuries from debris — an incident that would eventually lead to the Aeroscreen cockpit protection programme.
The aero kits continued into 2016 and 2017, with refinements from both manufacturers. Chevrolet and Honda both revised their packages across the three-year period, seeking performance gains on both oval and road or street courses. The aerodynamic requirements of high-speed ovals — where downforce management and drag reduction drove much of the design work — differed substantially from those of tight street circuits where mechanical grip was paramount, leading to complex aero kit configuration decisions for teams racing across the full calendar.
Criticism of the programme grew throughout its run. The cost of developing, manufacturing, and supplying unique aero components was significant for both manufacturers, and the expense filtered down to teams and car owners. Component breakage in incidents remained a persistent operational problem. Safety concerns were also raised, particularly regarding how complex aerodynamic elements behaved when cars made contact.
IndyCar announced the conclusion of the manufacturer aero kit programme after the 2017 season. For 2018, the series transitioned to a new universal aerodynamic kit, the UAK18, designed by Dallara with input from the series and its manufacturer partners. The new bodywork was developed in part to address the safety and cost concerns that had accumulated during the aero kits era, while maintaining some visual character distinct from the previous spec DW12 appearance.
The aero kits era is generally regarded as an interesting but ultimately unsustainable experiment — a period that confirmed how difficult it is to layer meaningful aerodynamic competition onto a cost-conscious spec series without introducing its own set of logistical and safety complications.