"Co-op allows up to four players to play through the campaign together. The leader selects the events, and the other players join them. All races become Team Races by default, the players versus the Drivatars. All events that are available in Horizon Solo are available in Co-op."
In this E3 video interview Ralph Fulton describes Campaign Co-Op mode: team members can share cars.
Is there a split screen (local multiplayer) mode in FH3?
The game does not support split screen play. See also LAN discussion thread.
(Written by Manteomax)