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Sep 17, 2025

Happy race week everyone!

Before getting into this I wanna thank those that helped me with proofreading or anything along those lines. And apologize for my constant nagging with questions like; 'is this good? does this make sense?' You all are very much appreciated <3

As I’m planning my comprehensive introduction to IMSA’s WeatherTech Sportscar Championship that I will be posting before the Rolex 24 next year (just like this WEC one I did). I spoke to a few people about what they would like to see and I primarily heard about people really wanting the basics before going into a potential deep dive before next season. Which is why I’m writing it now, so late in the season because Logan Sargeant has attracted so many new fans.

I’ve been a fan of IMSA and any type of sportscar/endurance racing for a really long time now, so I’m extremely happy to welcome any new fans. I hope this post is some form of help coming into IMSA for the very first time. I’m always happy to answer any questions following this though, and will be so throughout the rest of the season and into next year. Any questions are what really helps me make a more in-depth introduction. This post will be primarily aimed at fans joining because of Logan Sargeant, so I will mention him a few times and also go a little more in depth about the class he races in. But this ‘crash course’ should be useful for anyone wanting to know more about IMSA.

One thing I will clarify, which I have done before, but I kind of feel the need to do it every time I talk about IMSA. The IMSA WeatherTech SportsCar Championship (WTSC) is sanctioned by IMSA (International Motor Sports Association). IMSA is then a division of NASCAR.

Now IMSA sanctions a heap of series such as the IMSA Michelin Pilot Challenge, Mazda MX-5 Cup etc. So technically IMSA is not a series of its own, but a sanctioning body. However, the main series under said body (the WeatherTech SportsCar Championship) will often be referred to as simply "IMSA". This will be by fans, media, drivers and anyone really. And that will also be the case for me in this ‘crash course’, I might sometimes specify WTSC when talking about history but generally I’ll just refer to the championship as IMSA.

History

IMSA's history goes back way further than the current WTSC and I will dive deeper into that in my full intro. However, I want to keep this as easy to digest as possible so I'm only starting from when the current series was created.

In 2014 the United Sportscar Championship held its inaugural season after a merger by the American Le Mans Series and the Rolex Sports Car Series. In 2016 this series would be renamed to IMSA SportsCar Championship, this was also the year WeatherTech became their title sponsor.

Throughout the years leading up to this season, the class structure has changed a few times but the format of the series has remained largely the same.

While not comprehensive to IMSA, I have written about the history of women at the Rolex 24. So, if you’re interested, make sure to take a look. Also mentioned in the article, is Christina Nielsen who to this date is the only woman to win a title in the WTSC, which she did twice in the GTD class.

Calendar

Bold = Michelin Endurance Cup

There are still two races left on the calendar, the Battle on the Bricks at IMS and Petit Le Mans at Road Atlanta.

25-26 January | Rolex 24 at Daytona – 24 Hours

15 March | Mobil 1 Twelve Hours of Sebring – 12 Hours

12 April | Acura Grand Prix of Long Beach – 100 Minutes (GTP, GTD)

11 May | TireRack.com Monterey SportsCar Championship – 160 Minutes (GTP, GTD Pro, GTD)

31 May | Chevrolet Detroit Sports Car Classic – 100 Minutes (GTP, GTD Pro)

22 June | Sahlen’s Six Hours of the Glen – 6 Hours

13 July | Chevrolet Grand Prix (CTMP) – 160 Minutes (LMP2, GTD Pro, GTD)

3 August | Motul SportsCar Grand Prix (Road America) – 160 Minutes

24 August | Michelin GT Challenge at VIR – 160 Minutes (GTD Pro, GTD)

21 September | TireRack.com Battle on the Bricks – 6 Hours

11 October | Motul Petit Le Mans (Road Atlanta) – 10 Hours

Classes

GTP

GTP is IMSA's current top class and one of two prototype classes, it is the successor to the DPi category that ran from 2019 to 2022. The GTP class was created with the ultimate aim of the ACO, FIA and IMSA for these cars to compete against each other in the FIA WEC and in the IMSA WeatherTech SportsCar Championship and, therefore, to race in both the 24 Hours of Le Mans and the Rolex 24 at Daytona.

The GTP class allows cars built to LMDh (Le Mans Daytona h) and LMH (Le Mans Hypercar) specifications. All cars except for the Aston Martin, which joined this season, run to LMDh specification.

LMH These regulations leave scope for a wide variety of architectures and allow a front-axle hybrid system to be fitted. They are designed to a strict set of requirements dictating maximum power, drag coefficient, and weight. LMDh In LMDh, The chassis is built by one of four manufacturers, Dallara, Multimatic, Ligier or Oreca. And the cars have a spec Bosch Hybrid Unit. Beyond that (ICE, bodywork, electronics, suspension etc.) is done by the Manufacturer.

GTP has no restrictions on driver line-ups but as it's a professional class with a majority of factory teams, most line-ups will consist of Platinum and Gold-rated drivers.

LMP2

LMP2 is IMSA's second prototype class. The class features a spec drive-train and gearbox, using a Gibson V8 engine, and a selection of three chassis to choose from, of which the Oreca 07 has been the chassis of choice. So much, that every single LMP2 car on this year’s grid is an Oreca.

Driver line-ups have to consist of at least one Bronze driver. During all races but the Rolex 24 only one Gold or Platinum rated driver is permitted, during the Rolex 24 one Platinum and Gold Driver or two Gold drivers are permitted.

GTD Pro

One of two GT classes in IMSA, it replaced the GTLM class that ran ACO's GTE spec in 2022. GTD Pro utilizes FIA GT3 specifications just like WEC`s LMGT3 class does. GTD Pro driver line-ups have no restrictions.

GTD

GTD has been in IMSA since 2016 and runs to the same specification as GTD Pro. The only difference is the composition of driver line-ups. During all races but the Rolex 24 only one Gold or Platinum rated driver is permitted, during the Rolex 24 one Platinum and Gold Driver or two Gold drivers are permitted.

Below, a graph with all classes on it to further clarify the driver (rating) requirements in each class depending on race length. For an explanation on FIA’s driver categorization read more here (Page 53)

*ALL in this case stands for any driver rating is permitted (Bronze, Silver, Gold, Platinum)

Qualifying

After practice sessions all classes participate in their own qualifying session, this is also the first session that is broadcast, you’ll only be able to follow practice through live timing.

Qualifying is separate for each class, with a 20 minute session for GTP and 15 minutes for all other classes. The driver with the fastest lap in each class earns the Motul Pole Award and 35 points for pole. Only a single driver per car is allowed to qualify. In all classes teams can select any driver to qualify, except for LMP2 where the Bronze-rated driver has to qualify.

If qualifying is canceled, starting grids are set by team points and if a driver causes a red flag during qualifying, that driver will lose their fastest lap from the qualifying session.

Starts

IMSA races will go underway with a rolling start, each car ordered by qualifying time within their class, not overall. (I.e. if a GTD class car goes quickest among all GTD cars, including GTD PRO, It will not start ahead of any GTD Pro cars but only at the head of the GTD field).

The field is divided into two groups, a prototype group (GTP, LMP2) which will get the green flag first. And then moments after the GT group (GTD, GTD Pro)

Pit Stops

During pit stops, no one is allowed over the wall until the car comes to a full stop. Four crewmembers are then designated to perform tasks on the car, such as refueling and tire changes. The crew can also service other mechanical work if necessary, including changing brake pads and rotors, adjusting the aerodynamic wing, and repairing any damage from contact.

If a driver change is taking place, one extra crewmember is allowed over the wall to assist the driver stepping in by connecting the driver’s radio, air hoses, drink tube and safety belts.

Pitlane has a speed limit of 60 kph this will be strictly enforced for all cars driving in the pit lane. Anyone caught speeding must serve a drive-through penalty.

Neutralisations

Unlike WEC, IMSA only has one way to neutralize a race: a Full Course Yellow. This is sometimes called a "safety car period" by IMSA, but both refer to the same procedure. During this period, the pit exit closes from the time that the Safety Car (or the overall leader acting as the Safety Car) passes the last pit box.

Cars may enter the pits while closed to take emergency service when needed (e.g. flat tire, out of fuel). Emergency service is limited, mostly the bare minimum for the car to continue on track. After taking emergency service cars will then have to make another drive through and complete their service.

Following that, the Race Director will start the initial Pass-Around for any car that has its class leader behind it in the order circulating behind the Safety Car. It is the competitor’s responsibility to determine if their car is eligible for the Pass-Around. If a car is deemed to have joined the Pass-Around while ineligible, the car will have to serve a stop and hold for time equal to two race laps.

After that, the pits will reopen, all Prototypes will be able to pit within the first laps the pits are reopened. The GTD field in the subsequent lap. Any Car is permitted to pit on laps after the first two class-specific opportunities to pit are concluded.

Category Split & Class Split

Before the class split, there will be a Final Wave-By with the same rules as the initial Pass-Around. Prior to the restart, Race Control will conduct a Prototype/GT Category Split, followed by a GTP/GTD PRO Class Split, so the race restarts with GTP/LMP2/GTD PRO/GTD classes in order.

Race Control will announce “Prepare for the Category Split”. GTP and LMP2 Cars must move to the right side of the track and all GTD PRO and GTD Cars must remain in Single File and move to the left of the track and fall back. Once Race Control announces “Commence the Category Split”, GTP and LMP2 Cars must, on the right and in Single File, pass any GTD PRO/GTD Cars to take position at the front of the field behind the Safety Car.

Once the category split is done, Race Control will announce “Prepare for the Class Split”. GTP and GTD PRO Cars must move to the right side of the track. LMP2 and GTD Cars must move to the left side of the track and fall back. Once Race Control announces “Commence the Class Split”. GTP Cars must pass any LMP2 Cars on the right side of the track to take position ahead of all LMP2 Cars and behind the Safety Car. At the same time, GTD PRO Cars must, also on the right, pass any GTD Cars to take position ahead of all GTD Cars and behind the LMP2 Cars.

The conclusion of the class split is when the Safety Car lights are turned off and then the race will be restarted in single file, led by the overall leader.

As the concept was, slightly confusing.. and I found it really hard to explain. Below a short animation of the category and class split:

When the track goes green following a FCY and another FCY is called within 15 minutes, a short FCY will be called. For a Short FCY, after the Pass-Around, the pit lane remains closed until the last Car has passed the pit entry, the restart is announced by Race Control and the Cars are coming to the green flag. No Final Wave-By is performed.

If the short FCY exceeds 15 minutes, IMSA may convert the short FCY into a standard FCY. A short FCY is not followed by another FCY.

Classifications

Within the WTSC there are several championships. There are championships for drivers, teams and manufacturers. The season long driver championships is scored per the table below. Drivers in a car will get points for qualifying even if they don't qualify the car. Each class has its own standings.

The team's championships are scored the same. Each car entered is considered its own "team" regardless if it is a single entry or part of a two-car team. IMSA also recognizes a Car Manufacturer champion in the GTP, GTD PRO and GTD classes. Only the highest finishing car of each manufacturer will count, subsequent finishing cars from the same Manufacturer are not considered in the results and all other cars elevated in the finishing positions accordingly. (e.g. Manufacturer A finishes 1-2 at an event, and Manufacturer B finishes 3rd, Manufacturer A receives 1st place points (350 points) and Manufacturer B receives 2nd place points (320 points)).

Points for qualifying will be given to all drivers of said car.

Michelin Endurance Cup

Michelin Endurance Cup (MEC) points are awarded differently to that of the season-long championship. During the season, cars will continue to score points for the season-long championships but will also score MEC points in a separate championship during MEC races.

MEC Points are awarded based on the standings in each class at specific intervals. In the table down below, all intervals are written down per race. For example, during the 12H of Sebring points will be awarded at 4H and 8H into the race, and then also at the finish. The points distribution in the table below that counts for all of these intervals, P1 scores 5 points, P2 scores 4 points etc.

The points are awarded when the overall Race leader crosses the start-finish line after the set timestamp has passed, then followed by all subsequent cars.

Points distribution for the MEC:

Trueman & Akin Bronze Cup

Bronze rated drivers in both the LMP2 & GTD class will compete for the Trueman (LMP2) & Akin (GTD) Bronze Cup. This is specifically for amateur drivers who have established themselves as an outstanding driver alongside other professional pursuits away from the track.

The drivers that win these cups at the end of the season will receive an invite to the following year’s 24H of Le Mans. Points are scored in the same way as the season-long championship but have their own separate standings with every driver that is eligible.

How to watch?

IMSA.TV

YouTube (Includes Ads)

IMSA Radio (Sound Only)

These first two options are blocked in several countries where IMSA has broadcast deals, however it’s easy enough to use a VPN if it is blocked.

From the IMSA website on distribution:

In the US races can be streamed live in their entirety on NBCSports.com, the NBC Sports App with authentication or Peacock (Premium). Or on cable in the USA or NBC.

How to Watch in the Netherlands:

Ziggo Sport will broadcast WeatherTech Championship events in the Netherlands with Dutch commentary.

How to Watch in Canada:

REVTV will broadcast WeatherTech Championship events in Canada.

How to Watch in France:

AutoMotoTV - will broadcast WeatherTech Championship events with French commentary.

How to Watch in Germany:

Motorvision TV will broadcast WeatherTech Championship events in Germany with German Commentary.

How to Watch in New Zealand:

Sky TV will broadcast WeatherTech Championship race events for New Zealanders.