2015 United SportsCar Championship

The 2015 IMSA Tudor United SportsCar Championship (TUSC) season was the second season of the International Motor Sports Association's Tudor Championship, and the 45th overall season of the IMSA GT championship tracing its lineage to the 1971 IMSA season. It began January 24 with the 24 Hours of Daytona.

Classes
The class structure remained largely unchanged from 2014. 2015 will see the introduction of two awards for the top-finishing Pro-Am drivers in Prototype (P) and GT Le Mans (GTLM). The Jim Trueman Award will be given to the top finishing Pro-Am pairing in Prototype, while the Bob Akin Award will be for the top GTLM pairing. The top Pro-Am pairings from these classes at the end of the year will be given automatic entries to the 2016 24 Hours of Le Mans, with the Trueman award winner eligible for the LMP2 class, while the Akin Award winner would be for the LM GTE Am class. To be eligible for these awards, the drivers must at a minimum contest the North American Endurance Cup events.
 * Prototype (P)
 * Prototype Challenge (PC)
 * GT Le Mans (GTLM)
 * GT Daytona (GTD)

Race schedule
The 2015 schedule was released on August 10, 2014 and features twelve rounds.

Calendar changes

 * The events at Kansas Speedway and Indianapolis Motor Speedway have been discontinued.
 * A round at Lime Rock Park was added for PC and GTD.
 * The round at Canadian Tire Motorsports Park will see PC replace GTD alongside P and GTLM.
 * The IMSA Continental Tire Sports Car Challenge support series follows the same schedule as above in 2015 except for the street circuits of Long Beach and Detroit Belle Isle for a ten round season.
 * On October 31, 2014, the calendar was modified removing PC from the Virginia International Raceway round and adding the class to the round at Detroit Belle Isle alongside P and GTD.
 * The Monterey round would feature all four classes in a single event.

Prototype Challenge
All entries use an Oreca FLM09 chassis powered by a Chevrolet LS3 6.2 L V8.

News
On June 3, 2014, it was announced that Ford would be limiting itself to factory teams for the 2015 season.

Results
Bold indicates overall winner.

Points Systems
Championship points are awarded in each class at the finish of each event. Points are awarded based on finishing positions as shown in the chart below.

Drivers Points
Points are awarded in each class at the finish of each event. Drivers must complete a minimum driving time (outlined to teams prior to each event) in order to score points. A driver does not score points if the minimum drive time is not met.

In addition, for each car credited with a race start, each driver nominated in that car also receives one additional “starting point.”

Team Points
Team points are calculated in exactly the same way as driver points, using the point distribution chart and “starting points.” Each car entered is considered its own “team” regardless if it is a single entry or part of a two-car team.

Manufacturer Points
There are also a number of manufacturer championships which utilize the same season-long point distribution chart, minus the “starting points” used for the driver and team championships. (The “starting point” is not used in manufacturer championship points.) The manufacturer championships recognized by IMSA are as follows:
 * Prototype (P): Chassis Constructor; Engine Manufacturer
 * GT Le Mans (GTLM): Car Manufacturer; Tire Manufacturer
 * GT Daytona (GTD): Car Manufacturer

Each manufacturer receives finishing points for its highest finishing car in each class. The positions of subsequent finishing cars from the same manufacturer are not taken into consideration, and all other manufacturers move up in the order.
 * Example: Manufacturer A finishes 1st and 2nd at an event, and Manufacturer B finishes 3rd. Manufacturer A receives 35 first-place points while Manufacturer B would earn 32 second-place points.

The points system from the 2014 season is the same as in 2015.

North American Endurance Cup
The points system for the North American Endurance Cup is different from the normal points system. Points are awarded on a 5-4-3-2 basis for drivers, teams and manufacturers. The first finishing position at each interval earns five points, four points for second position, three points for third, with two points awarded for fourth and each subsequent finishing position. At Daytona (24 hour race), points are awarded at six hours, 12 hours, 18 hours and at the finish. At the Sebring (12 hour race), points are awarded at four hours, eight hours and at the finish. At Watkins Glen (6 hour race), points are awarded at three hours and at the finish. At Road Atlanta (10-hour race), points are awarded at four hours, eight hours and at the finish.

Like the season-long team championship, North American Endurance Cup team points are awarded for each car and drivers get points in any car that they drive, in which they are entered for points. The manufacturer points go to the highest placed car from that manufacturer (the others from that manufacturer not being counted), just like the season-long manufacturer championship.
 * For Example: In any particular segment manufacturer A finishes 1st and 2nd and manufacturer B finishes 3rd. Manufacturer A only receives first-place points for that segment. Manufacturer B receives the second-place points.

Prototype

 * Notes
 * 1 – All drivers of car #10 were moved to last in class at Daytona for exceeding maximum drive-time limitation.
 * 2 – The #7 of Starworks Motorsport withdrew from the 12 Hours of Sebring before Practice with only Scott Mayer and Brendon Hartley confirmed as drivers.

Prototype Challenge

 * Notes
 * 1 – Three drivers of car #8, Mirco Schultis, Renger van der Zande and Mike Hedlund, only scored one point at Daytona for exceeding maximum drive-time limitation.
 * 2 – Two drivers of car #11, Gustavo Menezes and Jack Hawksworth, only scored one point at Daytona for exceeding maximum drive-time limitation.
 * 3 – All drivers of car #16 were moved to last in class and only scored one point at Daytona for exceeding maximum drive-time limitation.
 * 4 – Two drivers of car #85, Chris Miller and Gerry Kraut, only scored one point at Sebring for exceeding maximum drive-time limitation.
 * Drivers denoted by † did not complete sufficient laps in order to score points.

GT Daytona

 * Notes
 * 1 – Three drivers of car #73, Jim Norman, Nelson Canache, Jr. and Kévin Estre, only scored one point at Daytona for exceeding maximum drive-time limitation.
 * 2 – Michael Avenatti, driving with four other drivers in car #81, only scored one point at Daytona for exceeding maximum drive-time limitation.
 * 3 – Two drivers of car #19, Ricardo Flores, Jr. and Jim Michaelian, only scored one point at Daytona for exceeding maximum drive-time limitation.
 * 4 – The #18 of Mühlner Motorsport America and the #009 of TRG-AMR North America withdrew from the 12 Hours of Sebring before Practice with only Connor De Phillippi and Dennis Trebing confirmed as drivers respectively.
 * Drivers denoted by † did not complete sufficient laps in order to score points.

Prototype

 * Notes
 * 1 – Car #10 was moved to last in class at Daytona for exceeding maximum drive-time limitation.
 * 2 – The #7 of Starworks Motorsport withdrew from the 12 Hours of Sebring before Practice with only Scott Mayer and Brendon Hartley confirmed as drivers.

Prototype Challenge

 * Notes
 * 1 – Car #16 was moved to last in class and only scored one point at Daytona for exceeding maximum drive-time limitation.
 * Cars denoted by † did not complete sufficient laps in order to score points.

GT Daytona

 * Notes
 * 1 – The #18 of Mühlner Motorsport America and the #009 of TRG-AMR North America withdrew from the 12 Hours of Sebring before Practice with only Connor De Phillippi and Dennis Trebing confirmed as drivers respectively.
 * Cars denoted by † did not complete sufficient laps in order to score points.

GT Daytona

 * Notes
 * 1 – Porsche was unable to score at Laguna Seca due to a technical infraction, so they did not get the 35 points the winner usually gets. Audi finished second in the manufacturers' championship that race, but they did not get the points for first place.

Tires' Championship
No North American Endurance Cup in the tires' championship