GPxPatch is a tool for the PC racing simulators Grand Prix 3 and Grand Prix 4. It was created by René Smit, with additional contributions by Marc Aarts, Laurent Rousseau and a whole host of others. It involves a simple download, installation and play procedure, and runs off a decrypted GP4.exe, which is available on a range of download sites. The program itself is mainly programmed in Visual C++ and assembly language.
The program contains four functions:
There are additional features as well, such as an "extended pause mode" where the player can take interesting screenshots by altering the onboard camera positions. Also, the program includes a 'Debug Mode' option where if there is a problem with the game, the debug will determine the problem in the form of a log file. For GP3 it enabled using a unique texture for each car making it possible for the first time to drive with 22 different car liveries.
GPxPatch is regarded as one of the must-have add-ons for the GPx Series, as it makes the gameplay much more enjoyable and worthwhile. After a three year break, GPxPatch version 3.92 was released which included several fixes and changes.