The IndyCar Series allows manufacturers to develop different types of engines, while every team uses the same chassis. Currently,
Dallara provides a specification chassis to all teams, with
Honda and
Chevrolet providing teams different engines.
Chassis 1996–2011 In the series' first season (
1996), 1992 to 1995 model year CART chassis built by
Lola and
Reynard were used. The first new Indycar came into being in 1997.
Tony George specified new technical rules for less expensive cars and production-based engines. The move effectively outlawed the
CART chassis and turbocharged engines that had been the mainstay of the
Indianapolis 500 since the late 1970s. won the
2000 Indianapolis 500. Starting with the 2003 season, the series rules were changed to require chassis manufacturers to be approved by the league before they could build cars. Prior to that, any interested party could build a car, provided it met the rules and was made available to customers at the league-mandated price. In total, four manufacturers have built IndyCar chassis. Dallara began producing Indycars for the 1997 season. The Dallara and G Force chassis were relatively evenly matched over their first few seasons, but eventually, the Dallara began to win more races. This caused more teams to switch to the Dallara, further increasing their success. As of 2017, a Dallara chassis has been used by 17 Indy 500 winners, although there have not been any competing manufacturers since 2008. Dallara was also tapped to build the
Firestone Indy Lights machines. After the withdrawal of factory support from
Panoz Auto Development, they are the only supplier of new chassis. The G Force chassis was introduced in 1997 and won the 1997 and 2000 Indy 500 races. In 2002,
Élan Motorsport Technologies bought G Force, and the chassis was renamed "Panoz G Force", and then shortened to "Panoz" in 2005. In 2003 a new model was introduced, and it won the Indy 500 in 2003–2004 and finished second in 2005. It fell out of favor starting in 2006, and by then, only one had finished in the top ten at Indy. Little factory support was given to IndyCar teams by Panoz after that point, as they had concentrated on their DP01 chassis for the rival Champ Car World Series. By 2008, only one Panoz saw track time, an aborted second-weekend effort at Indy, that resulted in
Phil Giebler being injured in a practice crash. during practice for the
2007 Indianapolis 500.
Riley & Scott produced IndyCar chassis from 1997 to 2000. Their initial effort, the Mark V, was introduced late in the 1997 season, severely limiting its potential market. It also proved to be uncompetitive. After Riley & Scott was purchased by Reynard, an all-new model, the Mark VII, was introduced for the 2000 season. It won in Phoenix, the second race of the season (driven by Buddy Lazier), but was off the pace at Indy and was quickly dropped by its teams. Falcon Cars was founded by
Michael Kranefuss and Ken Anderson in 2002 as the third approved chassis supplier for the 2003 season. One rolling chassis was completed and shown, but it was never fitted with a working engine and never ran. No orders were ever filled. Superficially, IndyCar machines closely resemble those of other open-wheeled formula racing cars, with front and rear
wings and prominent
airboxes. Originally, the cars were unique, being designed specifically for oval racing; for example, the oil and cooling systems were
asymmetrical to account for the pull of liquids to the right side of the cars. Later cars were designed to accommodate the added requirements of road racing. IR05 Indycar chassis driven by
Scott Sharp at the
2007 Bombardier Learjet 550 at
Texas Motor Speedway. Because of a schedule conflict, the Champ Car World Series spec
Panoz DP01, with a
Cosworth engine, was run in an IndyCar Series points event in the 2008
Toyota Grand Prix of Long Beach.
2012–2014 during practice for the
2012 Indianapolis 500. This initial version of the DW12 would be utilized during the 2012–2014 seasons. In 2010, IndyCar announced that it would officially adopt a single-make chassis formula, beginning in 2012 among a selection of proposals from interested parties, and set up the ICONIC (Innovative, Competitive, Open-Wheel, New, Industry-Relevant, Cost-Effective) Advisory Committee to make a final recommendation. Proposals were submitted and announced by BAT Engineering,
Dallara,
Lola,
Swift, as well as the radical
DeltaWing design that was penned by Ben Bowlby and financed by
Chip Ganassi. In July 2010, IndyCar announced that Dallara had won the contract to remain as the series' single chassis supplier. In 2012 the series adopted the Dallara IR-12 chassis as a cost control method, and IndyCar negotiated a price of $349,000 per chassis. The new specification also improved safety, the most obvious feature being the partial enclosure around the rear wheels, which acts to prevent cars ramping up over another vehicle's back end. This chassis was intended to support multiple aerodynamic kits, but introduction of these was delayed until 2015, with teams citing costs. After the events of the
2011 IZOD IndyCar World Championships the chassis was nicknamed
DW12 in honor of
Dan Wheldon. during Carb Day before the
2017 Indianapolis 500. This was driven with the
Honda version of the Separate Manufacture Aerokits that were used for the 2015–2017 seasons.
2015–2017 In 2015, teams began running aero kits developed by their engine manufacturers as a first-ever
Dallara DW12 facelift. The kits, while increasing speeds and offering a clear distinction between the two manufacturers, led to significant cost increases. Further, Chevrolet's aero kit was the more dominant with Honda only able to mount a competitive charge on ovals due to having slightly better engine power. While Honda was able to make gains in 2016, after two years of development the kits were frozen for 2017, and starting in 2018 all cars ran the same aero package again. To further help reduce costs, IndyCar allowed teams to shop for competitively priced non-safety-related parts such as brakes instead of mandating parts from specific suppliers. IndyCar had hoped to set a new speed record at the Indianapolis Motor Speedway by 2016 with the introduction of aero kits and the development work associated with them. However, after a series of safety concerns during practice for the 2015 Indianapolis 500 with the Chevrolet aero kit package, this did not come about.
2018–present The 2017 season was the third and final year contested with the
Chevrolet and
Honda aero kits outfitted to the
Dallara DW12 chassis. Beginning in 2018, all
DW12 Safety Cell chassis have been fitted with a universal bodywork kit. Digital renderings for the common bodywork kit, referred to as the 'IR18' car, were released in early May 2017 as a second facelift of
Dallara DW12. The car was officially unveiled in late July, and the universal aero kit became known as the UAK18 bodywork. during the
2018 Kohler Grand Prix at
Road America. The bodywork is inspired by
CART's 1990s and 2000s designs, with a more streamlined appearance. The redesigned aero kit reduces both aerodynamic downforce and team and manufacturer design development costs. The universal Aero Kit was designed without the wheel guards of the DW12 chassis, which were deemed ineffective and proved prone to breaking. The IR-18 also lacks an air inlet above the cockpit, a first for an IndyCar Series chassis (most Champ Car chassis had been designed that way). The new Aero Kit also has fewer small aerodynamic pieces that can become broken or dislodged, with the intent to reduce the amount of debris that ends up on the track and expenses from repairs. The "aeroscreen" cockpit protection was added in time for the 2020 season, and some minor modifications were eventually conducted to reduce the intense heat caused by stagnant air on the drivers.
Planned replacement Planning for a successor to the Dallara DW12 chassis was first publicly discussed on March 5, 2024, noting its age and the trend of open-wheel series replacing cars after five or so years, with the DW12 having last been revised in 2018.
Dallara will still remain as the series's official chassis builder, partner, and supplier for the IR-27 era. IndyCar announced on December 16, 2024, that it would begin wind tunnel testing of an all-new Dallara IR-27 chassis that is expected to début in the 2027 season. On June 12, 2025, it was announced that the planned all-new chassis will be delayed to 2028 and renamed as
Dallara IR-28.
Transmission and clutch For the transmissions, all IndyCar Series cars currently use an electronically actuated
AGS (
Assisted Gearchange System) 6-speed
semi-automatic sequential gearbox with an electro-pneumatically operated paddle-shift system and a pneumatic clutch with semi-automatic activation supplied by
Xtrac Limited since the 2008 season. All current IndyCar transmissions use
pneumatic actuation for the shifting and clutch, so the clutch is therefore only needed for launching the car from a standstill, and the clutch isn't required for gear shifting. From 1996 to 2007, all IndyCar Series cars used a hand-shifted 6-speed
sequential manual transmission with a shift lever, supplied also by Xtrac since 2000 until 2007. The clutches of all IndyCars are carbon with steel housing 3-plate clutch operated by foot-pedal in 1996–2011 later hand-paddle steering wheel clutch in 2012–present and provided by
AP Racing. Mechanical limited-slip differentials are permitted and constant velocity joint driveshafts are used. All IndyCar Series car drivetrains are currently
rear mid-engine with rear-wheel-drive layout.
Brakes Since the formation of the IndyCar Series in 1996, the brake package was slimmer carbon brake rotors with 4-pot calipers and carbon pads on all-oval races until 2011. Thicker steel brake rotors with 6-pot calipers and carbon pads were introduced in 2005 for road and street course races for stronger braking while approaching sharper turns. From 2012, IndyCar Series ditched the steel brake discs in favor of carbon brake rotors on all types of tracks but the caliper configuration remained the same as 1996–2011. PFC has supplied brake packages for all IndyCar Series cars since the 2017 season, initially supplying discs only, and later increasing their involvement from the 2018 season, supplying the calipers and rest of the brake packages. Previously, Brembo supplied the brake packages in 2012–2016 (full brake package), 2017 (caliper only), and Alcon in 2003–2011.
Wheels BBS and
O.Z. Racing have been supplying forged wheels since 1996. The wheels for all IndyCar Series cars are made of aluminum alloy. The size of IndyCar Series wheels have been on the front and on the rear since 1996; this size would be used until at least the 2022 season. 18-inch wheels will be adopted if the
Dallara DW12's successor comes out for the 2023 season onward.
Tires Firestone has been a tire supplier for the series since the 1996 season and sole tire supplier since 2000.
Goodyear had supplied tires from 1996 to 1999 for several teams before withdrawing their support. The IndyCar Series has run bespoke compounds since 1996 which were re-profiled in 2003. The front tire sizes are 305/45-R15 (10.0/25.8-R15) and the rear tire sizes are 415/40-R15 (14.5/28.0-R15). The compounds and construction of IndyCar Series tires are unique to each mounting position on the car. For road/street events, there are unique primary and alternative specifications for dry conditions, along with specially designed full-rain tires for all rain conditions; however, unlike in
Formula One which has intermediate rain tires for light-rain conditions, there are no intermediate rain tires due to cost. For oval racing, a single set of specifications is used based upon the configuration and speed of the track, as well as having the right rear tires slightly larger than the left rear (known as stagger) to aid in high-speed cornering.
Suspension The suspension of all IndyCar Series cars is double A-arm, pushrod, with third spring and anti-roll bar configuration multilink.
Cockpit and safety components 's car. 's car. All NTT IndyCar Series cars use carbon-fiber shell driver's seats with 6-point safety restraints. The cars' steering wheels are designed by
Cosworth with a system of buttons that allow the drivers to make adjustments to their cars in-race. From 2001 to 2017, IndyCar Series cars were equipped with Pi Research Sigma Wheel to display data, until they were replaced by Cosworth's Configurable Display Unit 4.3 display from 2018 on (although in 2018 some smaller low-budget IndyCar Series teams utilized old Pi Research Sigma Wheels instead of new Cosworth Configurable Display Unit 4.3 due to cost reasons). The cockpits of all IndyCar Series cars are open but protected by zylon, a foot protection bulkhead, and cockpit padding. Beginning in the 2020 season, the IndyCar Series implemented a cockpit protection system. This consists of a combination of the
Halo mandated in Formula One and a reinforced windscreen dubbed the "aeroscreen", provided by Red Bull Advanced Technologies, to lessen the probability of traumatic head injuries from flying debris.
Other components All IndyCar Series cars carry an Electronic Control Unit. Live telemetry is used only for television broadcasts, but the data can be recorded from the ECU to a computer if the car is in the garage and not on the track. Since 2007
McLaren supplied its Engine Control Unit (ECU) system for a few IndyCar Series teams and later became the standard Engine Control Unit (ECU) from the 2010 season. Previously,
Motorola supplied IndyCar Series ECUs in 2003–2009 for
Honda-powered cars, and
Denso supplied IndyCar Series ECUs in 2003–2005 for
Toyota-powered cars.
Zytek supplied IndyCar Series ECUs in 2002–2005 for
Chevrolet-powered cars. Rearview mirrors for all IndyCar Series cars are fully mandated.
Fuel Methanol At its inception, the IRL used
methanol racing fuel, which had been the de facto standard in American open-wheel racing since the
1964 Indianapolis 500 Eddie Sachs–
Dave MacDonald crash. Methanol provides a safer alternative to gasoline. It has a higher flash point, is easily extinguishable with water, but burns invisibly. With the IRL's introduction of night races in 1997, the burning of methanol fuel was visible for the first time, seen with a light blue haze. With this in mind, in an effort to make it more visible in case of fire during daylight hours, additional mixtures were placed in the fuel. As a safety feature, the methanol would burn with color.
Ethanol In 2005, the driver
Paul Dana brought the sponsorship of the Ethanol Promotion and Information Council (EPIC) to his IndyCar team. EPIC is a consortium of ethanol producers that advocate the increased use of
ethanol. EPIC was anxious to address public concerns of that era that ethanol use led to engine damage and poor performance when used in road cars. As a marketing effort, it was believed that sponsoring an IndyCar could be used as a tool to promote education and awareness of ethanol use and to curb the spread of erroneous information. Dana was killed in a crash in 2006, but the IRL had already begun a transition to
ethanol fuel. For the 2006 season the fuel was a 90%/10% mixture of
methanol and
ethanol. Starting in 2007, the league advertised "
100% Fuel Grade Ethanol," the first competitive series to utilize renewable fuel. The mixture was actually 98% ethanol and 2% gasoline, provided by
Lifeline Foods of
Saint Joseph, Missouri. The additives satisfy the U.S. government's demand that the alcohol is unfit for human consumption and add visible color in case of fire. However, 2010
São Paulo Indy 300, held in Brazil—outside of the U.S. regulations–utilized a full
E100 mixture, the first instance in the sport. To compensate for the loss of power due to the use of ethanol, the displacement was increased back to 3.5 liters. Since ethanol gets better fuel mileage than methanol, the fuel tank capacity was decreased. Compared to methanol, human contact with the current ICS fuel is much less harsh and the fumes much less irritating. The fumes are often compared with the sweet smell of apple cider or apple cobbler. Unlike methanol, ethanol is not caustic and does not cause chemical burns when it comes in contact with skin. It also is less polluting when spilled compared to methanol. In May 2010,
Sunoco became the official fuel of the series starting from mid-2010 through 2018. For the 2012 season, the ethanol fuel blend rate was reduced to 85% in a reference of road car relevance.
Speedway LLC took over as series official fuel supplier beginning from 2019 season, but the E85 formula remained to 2022. From 2023,
Shell USA (North American division of
Shell plc) would supply 100% ethanol-sourced fuel for the first time since 2011.
Fuel cell The fuel cells for all current IndyCar Series cars are made of rubber and are covered with a Kevlar-fitted blanket for extra protection in side impacts. Since 2012, the capacity has been . Previous capacities were in 2007–2011, in 2004–2006, and in 1997–2003.
Engines First generation (1996) Engine competition era (1996) The initial 1996 IRL season, as well as the first two races of the 1996–97 season, featured engines with specifications left over from the rival CART series competition. Those chassis/engine combinations were essentially under the same rules utilized by teams that participated in the
1995 Indianapolis 500, which was sanctioned by USAC. V-8 powerplants were allowed with of boost. The Menard-Buick V6 engine used in 1996, however, was an updated powerplant from the 1995 version. In addition, the V-6 stock block engines (Buick-Menard) were allowed of boost at all races, instead of just at Indianapolis. During the CART era, V-6 stock blocks were only allowed at all races outside of Indy, which was a decided disadvantage and left the engine out of favor.
Ford-Cosworth reluctantly provided support to teams wishing to run their older-spec engines in the IRL, a major point of contention for CART management, to whom Ford-Cosworth was an official engine supplier. The
Ilmor Mercedes V-8 engine, also a mainstay CART powerplant, was permitted, but the only time it was used was at the 1996 Indy 500 by
Galles Racing.
Second generation (1997–2011) Normally aspirated engines, competition era 1997–2005 Starting in 1997, IRL cars were powered by 4.0-litre
V8, four-stroke, piston,
Otto cycle,
methanol-burning, production prototype-based, naturally aspirated, internal combustion engines and electronic indirect multi-point port fuel injection, produced by
General Motors (under the
Oldsmobile Aurora label) and
Nissan (badged as Infiniti). Per IRL rules, the engines sold for no more than $80,000 (with an exception of full-works IndyCar Series teams that usually received free engines due to direct partnership with an each engine manufacturer), were rev-limited to 10,000 rpm, and weighed up to (excl. headers, clutch, ECU, spark box or filters). They produced around . This formula was used through 2003. In 2004, in the wake of several crashes including the fatal crash of
Tony Renna and the severe crash of
Kenny Bräck, the displacement was reduced to 3.0 liters using the existing engine blocks to curb top speeds (started from the
2004 Indianapolis 500). Infiniti's engines, though reliable, were significantly less powerful compared to the Auroras in 1997, leading many of the teams that had initially opted for the Infiniti to switch. By the end of the 1998 season, only a handful of low-budget teams were using the Infiniti, however, early in the 1999 season
Cheever Racing, a well-funded team, was brought on to develop the engine with team owner
Eddie Cheever expanding the team to two cars and bringing on his brother
Ross Cheever as a test driver. By 2000, the engine had improved markedly and Cheever captured the marque's first win at
Pikes Peak International Raceway. Despite the success, few teams made the switch to the Infiniti and the company left the series after the 2002 season to focus on powering the league's new
Infiniti Pro Series (now Firestone Indy Lights) cars. As part of General Motors' discontinuance of the Oldsmobile brand, the Olds engine was rebadged as Chevrolet starting with the 2002 season. The effort would lack in competitiveness against Toyota and Honda, which came to the IRL in 2003 from the rival CART series. In August 2003, Chevrolet announced to the public its "Gen IV" motor, a rebadged
Cosworth engine, for competition. At the time, Cosworth was owned by Ford. On November 4, 2004, Chevrolet stated that it would be ending its IRL engine program effective with the end of the 2005 season, citing costs that exceeded value, according to then
GM Racing Director Doug Duchardt, "The investment did not meet our objectives." Toyota won its first race in Miami, as well as the Indianapolis 500 and the series title. However, Toyota had just one podium in the last seven races of 2004, and only Penske Racing fielded competitive Toyota-powered cars in 2005, while Honda became the series' dominant engine manufacturer. In November 2005, Toyota company officials announced the company's withdrawal from American open-wheel racing and the immediate discontinuation of its IRL program, coinciding with its entrance into
NASCAR's Craftsman Truck Series in 2004, and its discontinuation of its
IMSA program.
Single-manufacturer spec engine era (2006–2011) After
Chevrolet and
Toyota elected to shut down their IRL involvement after 2005 season (
Chevrolet temporarily hiatus from IndyCar Series for six years while
Toyota USA elected to focus on
NASCAR involvement), Honda became the only standard spec-engine manufacturer in the IndyCar Series starting in 2006 and continued in that capacity through 2011 as it was announced by Indy Racing League president & chief operating officer Brian Barnhart and
Honda Performance Development president Robert Clarke on December 15, 2005. The IndyCar Series carried on with only one engine manufacturer in spite of the television agreement required at least two or three engine manufacturers to participate in the series to ensure future continuity. The Honda Indy V8 engine was partnered and co-developed by
Ilmor, which is part owned by
Roger Penske for tune-up, engine maintenance, arrangement and trackside support. The engine displacement was reverted from beginning from 2007 season. During that time, since the IndyCar Series had only one engine manufacturer, Honda focused on minimizing engine failure and minimizing costs instead of defeating rivals. As such, the engines were moderately de-tuned. The engines proved themselves to be quite durable—there had been no engine failures at Indy from 2006 to 2010, which also lowered the number of crashes. Most of the engines, including those used for the Indy 500, are used for multiple races and were intended to last between rebuilds. The Honda engines were only available via lease arrangement from Honda, which, for the 2010 full season, cost $935,000 U.S. per season, per car. IndyCar Series engines were rev-limited to 10,300 rpm and produce approximately 650 hp. A 'push-to-pass' system was intermittently adopted since the middle portion of the 2009 season, which increased the numbers to 10.500 rpm and 690 hp when employed. The valve train is a dual overhead camshaft configuration with four valves per cylinder. The fuel feed of Honda Indy V8 engine was an electronic indirect multipoint port fuel injection. The crankshaft is made of alloy steel, with five main bearing caps. The pistons are forged aluminum alloy, while the connecting rods are machined alloy steel. The electronic engine management system is supplied by Motorola, firing a CDI digital inductive ignition system. The engine lubrication is a dry-sump type, cooled by a single water pump. In 2009, Honda froze the Indy V8 engine development for the 2009–2011 seasons due to Honda focusing on a new third-generation V6 turbo engine for the 2012 season.
Third generation (2012–present) The current, third-generation IndyCar formula was introduced in 2012 including two new manufacturers, and marked the return of the IndyCar Series engine manufacturer competition war since the 2005 season. The engines are now fuel-efficient DOHC 2.2-liter twin-
turbo V6 with four-stroke piston Otto cycle developing an estimated 550–750
hp depending on the level of boost used and no inter-cooling systems. They are limited to 12,000
rpm and a weight minimum of . Engines are currently supplied by Chevrolet and Honda. Since the 2012 season,
McLaren has supplied its TAG-400i
engine control unit. The current engine fuel injector delivery now combines direct and electronic indirect injection which produces roughly of rail pressure. No fuel flow restriction exists in the IndyCar Series engine configuration.
Chevrolet returned to the series in 2012 to provide all-new, Ilmor developed and engineered, V6 twin-turbocharged engines after six-year hiatus while
Honda still remain committed to the series also to provide all-new V6 single-turbocharged engines in the same year.
Lotus Cars provided an engine developed by
Judd in 2012, but left the series in 2013 after lack of interest from teams in running the underdeveloped and uncompetitive Lotus engine. The electric push-to-pass overtake system was reintroduced during the
2012 Honda Indy Toronto race, and is still in use today. The electric overtake system produces roughly with a duration lasting between 6 and 200 seconds. This system is rechargeable, and its duration of use varies based on the track's dimensions.
Porsche expressed interest in joining the series as a third engine supplier in 2019. Ultimately Porsche backed out when IndyCar refused to allow them to field a hybrid powertrain. Coincidentally, IndyCar announced its plans for a hybrid powertrain one month later. Chevrolet was the first engine manufacturer to utilize the twin-turbocharged configuration alongside Lotus in 2012 while Honda was utilized the single-turbocharger in 2012–2013. Honda abandoned the single-turbocharged after 2013 in favor of twin-turbochargers from 2014 until the present. From 2024 season onwards the
hybrid systems will be introduced, consisting of a multi-phase motor, inverter, and battery that will create energy recovery from the car's braking system as well as current engine displacement still remained.
Turbocharger Having been absent since 1997, turbochargers were reintroduced for the start of the
2012 season. The turbo configuration that has been mandated since 2014 is a twin-turbo with the pressure range restricted to depending on track shape. American turbocharger company
BorgWarner is the exclusive supplier of turbocharger kits, with all cars since the 2014 season using the EFR7163 model in order to save costs. Previously the BorgWarner EFR9180 single turbo was used exclusively by Honda-powered cars, while BorgWarner EFR6758 twin turbos were used by Chevrolet and Lotus (2012) powered cars. Usually turbocharged-engined gasoline cars incorporate
intercoolers, but IndyCar Series cars do not use an intercooler kit to avoid additional weight;
ethanol fuel burns at lower temperatures which helps keep the engine cool.
Spark plugs Bosch (
Chevrolet) and
NGK (
Honda) have provided spark plugs for all IndyCar Series cars since 2012. Previously
NGK was an exclusive spark plugs supplier in 2006–2011 when
Honda was the standard IndyCar Series engine supplier. Previously
Denso also was a sparkplugs supplier in 2003–2005 for
Toyota-powered cars.
Performance The current IndyCar Series car top speed is approximately on the
Indianapolis Motor Speedway oval layout only. On intermediate and long ovals the top speed is approximately , and on road/street courses and short ovals, it is approximately depending on downforce setup. ==Racetracks==