Launch parameters

To add a launch parameter, go into Steam, find Raceroom in your library list to the left and right-click it, select properties, and there should be a launch field.

Hardware acceleration
To enable hardware acceleration of web menus, the game can be started with -cefEnableGPU (however, depending on GPU and driver, the performance can be disappointing, sometimes even worse)

HUD Overlay
HUD overlay can be enabled with -webHudUrl For example: -webHudUrl=https://otterhud.github.io/

Spectator mode
Using -broadcastUrl=http://localhost:9090 will enable you to spectate Multiplayer server without taking up a driver slot. Furthermore you can overlay a website onto the screen, so you can for example stream event, with grid positions on the screen.