GRID multiplayer allows you to race online against other people, up to 16 in a single session.
Quick match events consist of a set of 3 races which are randomly selected from the pool of challenges found in singleplayer career.
It is possible to become the lobby "host", however this provides no additional options in quick matches.
Custom matches allow you to create a custom event to your liking. It is either invite only, available to your friends on the respective platform or console, or publicly visible in Session Search.
Like in quick match, it is possible to become the lobby "host". Hosts in custom matches can change some lobby settings.
In session search you can find custom matches and lobbies that fit the given search criteria.
When joining a lobby players enter a game mode called Skirmish, where they can crash into one another with the Jupiter Eagleray Mk5. This somewhat resembles Demolition Derby from earlier GRID titles, however there is considerably less (optical) damage and no rounds or other objectives to be completed.
During this period players may select their car for the next race via the menu.