The chassis was born from IndyCar's 2010 ICONIC Plan (Innovative, Competitive, Open-wheel, New, Industry-relevant, Cost-effective), which solicited proposals from BAT Engineering, Dallara, DeltaWing, Lola, and Swift. IndyCar selected the Dallara proposal in July 2010. The resulting car centered on a core "IndyCar Safety Cell" rolling chassis priced at $349,000, with separate aerodynamic kits offered by manufacturers.
Dan Wheldon, the 2011 Indianapolis 500 winner, conducted the first official chassis test at Mid-Ohio in August 2011. Following Wheldon's death at Las Vegas Motor Speedway on October 16, 2011, during the final race of the previous chassis era, Dallara renamed the car the DW12 in his honor — continuing a naming tradition established by French constructor Ligier, which named cars after fallen driver Jo Schlesser.
The DW12 made its race debut at the 2012 Honda Grand Prix of St. Petersburg. Will Power of Team Penske took the inaugural pole position, while Hélio Castroneves won the first race. The car quickly proved its competitiveness at Indianapolis, where its first three 500-mile races produced 136 lead changes, including a record 68 in 2013.
During these early seasons, all teams ran an identical Dallara aerodynamic package, which kept costs controlled while providing a level competitive platform.
For the 2015 season, IndyCar introduced manufacturer-specific aero kits. Honda partnered with Wirth Research and Chevrolet partnered with Pratt & Miller to develop rival packages. Chevrolet's kits held an edge in the first season, winning the majority of races, but controversy arose at the Indianapolis 500 when three Chevrolet-powered cars experienced dangerous flip-over crashes. This prompted mid-season rule tweaks and safety reviews.
Safety upgrades implemented in 2016 included domed skids and Zylon bodywork tethers, introduced following the death of Justin Wilson at the 2015 ABC Supply 500 at Pocono Raceway, where he was struck by debris from a crashed car. Manufacturer kits continued through 2017 before a development freeze was imposed ahead of a planned universal kit return.
In March 2017, IndyCar announced a complete aerodynamic redesign: the UAK-18. The base DW12 safety cell chassis remained largely unchanged, but the rear-wheel guards and various winglets were removed after research showed they provided limited safety benefit while breaking easily. The new aerodynamic package drew visual inspiration from classic Indy cars of the 1980s and 1990s and shifted more downforce generation toward ground effects rather than wings.
The UAK-18 era also brought new cockpit equipment, including the Cosworth CCW Mk2 steering wheel and the Configurable Display Unit 4.3 dashboard for most teams. Driver comfort was improved through slightly enlarged cockpit dimensions.
Cockpit protection followed in subsequent seasons: an Advanced Frontal Protection debuted at the 2019 Indianapolis 500, followed by the full Aeroscreen developed by Red Bull Advanced Technologies for the 2020 season. The Aeroscreen became a defining visual feature of the contemporary IndyCar car.
IndyCar had originally planned to introduce hybrid powertrains for 2023, but supply chain disruptions and manufacturer requests for more development time delayed the rollout. A partial hybrid system — a 60 hp electric motor coupled to a 320 kJ capacitor — was instead introduced partway through the 2024 season at the Honda Indy 200 at Mid-Ohio, bolted onto the existing 2.2-liter twin-turbocharged V6 engines used by Honda and Chevrolet.
A successor chassis, announced in December 2024, is planned to enter service from the 2028 season, replacing the DW12/IR18 after more than a decade and a half of continuous service.
The DW12 was the second Dallara IndyCar chassis to be associated with a fatality during competition. Justin Wilson died at the 2015 ABC Supply 500 at Pocono Raceway after being struck on the helmet by the nose cone of a crashed car. As of the end of the 2025 season, this remained the last fatality in IndyCar Series competition.
The IR18 is the marquee open-wheel car in iRacing, where it is used as the vehicle for the service's official IndyCar Series licensed content. The simulation models the UAK-18 aerodynamic specification, including the Aeroscreen. It is used across iRacing's oval tracks — including virtual replicas of Indianapolis Motor Speedway, Daytona, and Pocono — as well as road courses, reflecting the car's real-world versatility. The IR18 in iRacing is one of the most technically demanding cars on the service, requiring users to manage oval-specific setup elements such as stagger, wedge, and tire temperature that are largely absent from road-course-only machinery.