I'd like to have an API to read and set the settings of at least some parts of the UI so that the community can add programs which control parts of the game. A prime example is AC's Content Manager which completely replaces the car/opponents/track selection. A different example is allowing Crew Chief to use some of the features it already has for other games such as selecting how much fuel to put in at a pit stop (though that's perhaps more "Game controls" than "UI"). Another use case is this program I wrote which provides a simple way to set the graphics settings with the aim of gathering up all the knowledge in dozens of posts on the subject and much clicking of options and replace it with a few questions and an algorithm to choose a set of settings: At present it works by reading rF2's data files and editing them which means it can only work before the game is loaded but an API would mean it could work in the background and change settings before each race. It uses these inputs from the game the number of AI (or an estimate of number of drivers for multiplayer) the types of car (it has its own data on the graphics load of the cars) the track (it has its own data on the graphics load of the tracks) whether VR is being used (or triple screens) with an API it could also fetch whether rain is possible whether there will be racing in the dark whether to use pretty graphics for a replay leaving only the player's input of how powerful their PC is (set and forget) and whether they prefer frame rate or eye candy (may not change often). Once it has those inputs it chooses which of a set of graphics settings to write into player.json Heading off into dreamland another use case I can imagine a "Race engineer" program which reads the telemetry from the existing Shared Memory API and offers to make changes to your car setup. Who knows what else the hive mind of rFactor modders could come up with?