Gran Turismo 3: A-Spec is a 2001 sim racing video game developed by Polyphony Digital and published by Sony Computer Entertainment for the PlayStation 2. It is the third installment in the Gran Turismo series. During its demonstration at E3 2000 and E3 2001, the game was known under the working title Gran Turismo 2000.

With previous titles being developed for the original PlayStation, Gran Turismo 3 marked the series' first foray into the sixth generation of video game consoles. Originally slated for a 2000 release as a launch title for the PlayStation 2, the game's development primarily focused on taking advantage of the console's newfound hardware capabilities. While compromising on the number of available vehicles (180, as opposed to 650 in Gran Turismo 2), the game was a significant leap forward in terms of graphics, physics, sound design, car modelling, opponent AI, environments and technical performance.

Like its predecessors, the game released to critical acclaim and was a commercial success. It went on to become the best-selling game in the series to date, the best-selling PlayStation 2 exclusive, and the second best-selling PlayStation 2 game (behind only Grand Theft Auto: San Andreas), having sold over 14.8 million copies since release. It is considered one of the greatest video games ever made. A landmark shift to the next generation of consoles, it is often cited as a turning point for the series and the sim racing genre as a whole. Its successor, Gran Turismo 4, was released in December 2004.

The objective of the game is to win all the provided races, championships, complete license tests and achieve 100% game completion. Every 25% of the game completed results in the player being awarded a car as a special prize. For GT3, the Gran Turismo Mode (Simulation Mode in the North American version) has a reorganized layout, with a more structured and progressive arrangement of races and challenges. Races vary from short beginner events to multi-hour endurance races and also rallying events against an opponent. In addition to these modes, car shops are now organized by country and then by manufacturer.

The Arcade Mode is reorganized in "stages"; these stages are made up of 5 or 6 tracks pooled from all available tracks in the game, including both road and rally races. To get to the next stage, all tracks on a stage must be completed on Easy difficulty or higher. By beating the stage on Normal or Difficult, additional cars are unlocked as well for play in any mode of Arcade Mode (including two-player battle and time trial).

GT3 features 19 race courses, 14 of which have reverse variants and 4 of which are dirt tracks. Most of these circuits are at fictional locations, but California's Laguna Seca Raceway and Côte d’Azur (which is heavily based on the Monaco Grand Prix circuit) are not.

Other changes include the omission of the ability to "race modify" or add downforce to production cars, removal of suspension damage, and the absence of torque limits for races. Race modifications would make a return in 2010's Gran Turismo 5 for the PlayStation 3, but were again omitted in the following game.

New to the franchise, GT3 also contained unlicensed versions of six actual Formula One cars, labelled as F686/M, F687/S, F688/S, F090/S, F094/H and F094/S (in the Japanese and American versions) that the player could win from endurance races. In the Japanese and American versions, the name of each car denotes various pieces of information (such as the amount of cylinders in the engine, the year the chassis was raced, and its driver, respectively). For example, the aforementioned F094/S was the 10-cylinder, 1994-season car driven by Ayrton Senna, whereas the F686/M represented the 6-cylinder, 1986-season car driven by Nigel Mansell. In the PAL release, however, there were only two F1 cars, not obviously based on any real-life counterparts and instead labelled as Polyphony 001 and 002 respectively.