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Featured Image by Osajus Photography on Flickr

Are you new to Sports Cars Racing? Curious about the differences between DPi & LMP2? No worries, we’ve got you covered. Ahead of the resumption of motorsport worldwide, we’ve decided to produce articles introducing Sports Car Racing to our readers. Part 5 is an in-depth introduction to the IMSA WeatherTech Sports Car Championship, discussing the history and the categories.

The IMSA WeatherTech SportsCar Championship, better known as the WeatherTech Championship, or the WTSC in short, is an endurance racing championship organized by the International Motor Sports Association (IMSA).

The championship had its inaugural season in 2014, consisting of 13 races, with 9 Sprint races and 4 Endurance Races. Not all classes participated in every sprint race. The inaugural championship in 2014 marked the reunification of Sports Car Racing in America, following 16 years of division between the IMSA GT Championship/American Le Mans Series and the United States Road Racing Championship (USRRC)/Grand-Am Rolex Sports Car Series (RSCS).

The Championship is unique in that it features a “championship within a championship”, the Michelin Endurance Cup (MEC), formerly known as the Tequila Patron North American Endurance Cup (TPNAEC), which is available in all classes. The GTD class also features a similar competition, the WeatherTech Sprint Cup, for the class at the sprint events of the calendar.


Initial Merger Announcement

On September 5, 2012 it was announced that the Grand-Am Road Racing sanctioning body would merge with the International Motor Sports Association, and as such, both bodies would merge their premier sports car series, the Rolex Sports Car Series and American Le Mans Series, with the planned series being set to begin in 2014.

On January 8, 2013, the preliminary class structure for the new merged series was unveiled. The Daytona Prototype class the RSCS would combine with the ALMS’s P2 class, and the DeltaWing to form the Prototype Class. The Le Mans Prototype Challenge (LMPC) class would also be carried over, with the Oreca FLM09 being continued to be used, although the class would switch to using Continental Tyres. The GT class of the American Le Mans Series would remain unchanged, while the RSCS Grand-Am GT was announced to be combined with the American Le Mans GTC category to form a new GT class. At the time, it was also announced that the RSCS’ GX class would remain separate. This announcement left the P1 category of the American Le Mans Series to be the only class which would be cut from the new combined series.

On the 14th of March 2013, at the Chateau Élan Hotel and Conference Center located alongside the Sebring International Raceway, American Le Mans series CEO Scott Atherton announced IMSA would continue as the sanctioning body for the new series. At the same event, the name for the merged series was unveiled: United SportsCar Racing, alongside its’ class structure, which remained largely similar to that which was announced in January, although the GT classes were renamed. ALMS’ GT class became renamed as GT Le Mans (GTLM), while the GA-GT & ALMS GTC combined class was to be known as GT Daytona (GTD). However, on 19th July 2013, it was hinted that the GX class would be folded into the GTD class, with Atherton stating:”  the GX cars are close enough in performance that a merger of GX into the GT Daytona category is not that much of a reach,”

On 31st July 2013, a tire partnership was announced, with Continental Tire serving as the exclusive tire supplier for the Prototype, Prototype Challenge and GT Daytona classes. Continental would continue to do so until the 2018 season, when it was replaced by Michelin for the 2019 season.

Later, on the 12th of September 12 2013, Tudor was announced as the title sponsor for the series, which was named the United SportsCar Championship.

Post Merger

The 2014 calendar saw a total of 13 races, with 4 races (Daytona, Sebring, Watkins Glen and Petit Le Mans) forming the TPNAEC.  All circuits were carried over from the 2013 schedules of both the American Le Mans and Rolex Sports Car Series. However, several circuits were dropped, including long-time sports car venues at Lime Rock Park and Mid-Ohio, as well as Barber and Baltimore.

The 2015 calendar saw the calendar reduced to 12 races, with the rounds at Kansas and Indianapolis dropped in favour of a new round at Lime Rock Park for the GTD & PC classes. GTLM saw the loss of Dodge, who had announced to be leaving the series in December 2014. On August 8, 2015, WeatherTech was announced as the new title sponsor for the series, renaming the series to the WeatherTech SportsCar Championship, starting with the 2016 season. This was despite TUDOR having initially signed a 5-year contract in 2013 to serve as title sponsor.

2016 saw the calendar remain at 12 races, with no rounds added or removed. Owing to the high car counts for the round at Laguna Seca, the round featured 2 races, split into 1 race for the GTLM & Prototype class and the GTD & PC classes. The 2016 was the last season to feature the Generation 3 Daytona Prototypes, alongside the Open-Cockpit LMP2s.

2017 saw the calendar remain at 12 races, with no rounds added or removed once again. The round at Circuit of the Americas was ran as a standalone round for the first time; past editions of the round, previously known as Lone Star Le Mans was held as part of the 6 Hours of Circuit of The Americas weekend. The season saw the introduction of the new Daytona Prototype International cars, alongside the new 2017 “Licensed Chassis” LMP2 cars in the prototype class. 3 cars were built to the new DPi regulations for the 2017 season: The Cadillac DPi-V.R, Nissan-Onroak DPi, and the Mazda RT24-P. This season was also the final season for the Prototype Challenge class; the Oreca FLM09 was almost 8 years old, having first been introduced in 2009 for the Formula Le Mans Cup.

2018 saw the calendar remain at 12 races, although the round at the Circuit of the Americas was dropped, being replaced by a round at the Mid-Ohio Sports Car Course. The Prototype class saw the introduction of a new DPi car, the Acura ARX-05.

2019 saw the calendar remain at 12 races, with no rounds added or removed. The championship returned to a 4-class structure, following the division of the Prototype class into the Daytona Prototype International (DPi) Class, and the Le Mans Prototype 2 (LMP2) class. The DPi class would be the lead class of the championship, and featuring teams with full professional lineups running DPi cars, and Balance of Performance (BoP). The LMP2 class would be the lower prototype class in the championship, featuring LMP2 cars with Pro-Am lineups. No BoP was applied in the LMP2 class. 2019 also saw the introduction of the WeatherTech Sprint Cup, for the GTD class, comprising of all sprint events in the championship, barring Long Beach, where GTD did not participate.

Originally for the 2020 season, the calendar was to have 12 races, with no new tracks added or removed from the schedule. However in the wake of the global Coronavirus Pandemic, a revised calendar was issued on 15th of May 2020, with a reduced 11 race calendar. This calendar is inclusive of the 2020 Rolex 24 at Daytona, which had already been run prior to the global outbreak

Class Overview

For a detailed guide between the classes, visit Part 2: Prototypes & Part 3: GTs.

Daytona Prototype International

Denoted by White Sticker with Black Font, White Number on Black Background.

#55 Mazda RT24-P Mazda Team Joest Image by Osajus Photography on Flickr

Introduced in 2017, the Daytona Prototype International (DPi) class is the spiritual successor to the original Daytona Prototypes. DPis are standard ACO/FIA homologated 2017 LMP2 chassis fitted with IMSA-homologated, manufacturer-designed, and branded bodywork and engines

The class utilises Balance of Performance, with aerodynamic adjustments, fuel capacity adjustments, weight changes, turbocharger boost and air restrictor size changes. Wind tunnel and dynamometer testing also performed on cars to establish a baseline specification for all new cars.


Denoted by White Sticker with Blue Font, White Number on Blue Background, alongside Blue Mirrors and Wing Endplates

#38 Performance Tech Motorsports Oreca 07 – Image by Corey Fonseca on Flickr

The second tier Prototype class in the FIA World Endurance Championship. It is a Pro-Am class in all championships where it is used and all teams must have one Amateur driver, who may be either a Bronze or Silver rated driver.

All cars in this category have been closed cockpit since 2017. Costs are tightly controlled in this category, with chassis price capped at 483 000€, only 4 chassis built by the 4 licensed chassis manufacturers (Ligier, Oreca, Dallara, Riley-Multimatic) and a spec Gibson engine can be utilised in the class. Bodywork in the class is also homologated and can only be altered under a “Joker” upgrade once during the current homologation cycle. 2 aerodynamic configurations are used: A high-downforce kit for use on all tracks, and a low drag kit for Le Mans


Denoted by White Sticker with Red Font, White Number on Red Background.

#3 Corvette Racing Corvette C7.R – Image by Alexandria Bates on Unsplash

The GTE class is used in the GTLM class of the WeatherTech Championship. The class had its origins in the N-GT class of the FIA GT Championship, which was renamed as GT2 in 2005. The GT2 class was later renamed as LM GTE in 2011, after the ACO removed the GT1 category from its sanctioned competition.

Unlike in the WEC, there is no Pro/Am class division in the category.

Engine size is limited to 5.5L for Naturally Aspirated engines, and 4L for Forced Induction engines, although waivers may be given. Engine-based Traction Control is allowed, and is the only driver aid allowed. Four-wheel drive is banned. Balance of Performance is applied.


Denoted by White Sticker with Green Font, White Number on Green Background. Green rear wing endplates and headlights with yellow lenses.

#14 AIM Vasser Sullivan Lexus RC F GT3 – Image by Corey Fonseca on Flickr

Instead of utilizing a second GTE class for Pro-Am lineups, the WeatherTech Championship utilises Group GT3 cars to form it’s second division of GT racers.

Points System

WeatherTech Sports Car Championship

Points awarded based on the final finishing position of the car at the end of the race.


Michelin Endurance Cup (MEC)

For the MEC, a different scoring system has been adopted. Points distributed at race intervals for both drivers, teams and manufacturers.
Daytona 24: Hour 6/12/18/24
Sebring 12: Hour 4/8/12
Watkins Glen 6: Hour 3/6
Petit Le Mans (10 hours): Hour 4/8/10

Position123Other Classified

2020 WTSC Calendar

RndRaceDuration ClassesCircuitDate
1Rolex 24 at Daytona24 HoursAll*Daytona International Speedway – Road CourseJanuary 25-26
2WeatherTech 2402 hours, 40 minDPi, GTLM, GTDDaytona International Speedway – Road CourseJuly 4
3Cadillac Grand Prix of Sebring2 hours, 40 minAll**Sebring International RacewayJuly 18
4Road Race Showcase at Road America2 hours, 40 minAllRoad AmericaAugust 2
5Michelin GT Challenge at VIR2 hours, 40 minGTLM, GTDVirginia International RacewayAugust 23
6Sahlen’s Six Hours of the Glen6 HoursAllWatkins Glen International – Grand Prix Course (with Inner Loop)September 6
7Northeast Grand Prix2 hours, 40 minGTLM, GTDLime Rock ParkSeptember 12
8Acura Sports Car Challenge at Mid-Ohio2 hours, 40 minDPi, GTLM, GTDMid-Ohio Sports Car CourseSeptember 27
9Motul Petit Le Mans10 HoursAllRoad AtlantaOctober 17
10IMSA Monterrey Grand Prix2 hours, 40 minAllWeatherTech Raceway Laguna SecaNovember 1
11Mobil 1 12 Hours of Sebring12 HoursAllSebring International RacewayNovember 14

* At the 2020 Rolex 24 at Daytona, LMP2 scored points only towards the MEC
** At the 2020 Cadillac Grand Prix of Sebring, GTD only scores points towards the WeatherTech Sprint Cup

Titles Awarded

Drivers’ Titles

DPi Drivers’ Championship
LMP2 Drivers’ Championship
GTLM Drivers’ Championship
GTD Drivers’ Championship

Teams’ Titles

Every car is considered as its own individual team, regardless of the number of entries submitted by each team.

DPi Teams’ Championship
LMP2 Teams’ Championship
GTLM Teams’ Championship
GTD Teams’ Championship

Manufacturers’ Titles

Only the top-finishing car for each manufacturer is awarded points

DPi Manufacturers’ Championship
GTLM Manufacturers’ Championship
GTD Manufacturers’ Championship

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