The Forza Horizon Rally Expansion Pack adds 5 new rally cars (some being modified cars already existing in game) and seven brand new rally courses each containing 4 stages for the player to race, drift, and crash their way to becoming the Forza Horizon Rally Champion.
The 5 new cars include:
In addition to new cars, there are new parts included with the rally expansion to modify existing cars from the base game to Rally suitable drives.
The 7 rallies are (and their winnings):
Each rally contains 3 stages that are parts of a longer track divided into smaller stages. The fourth and final stage of each rally is the full track.
All of the rally tracks are custom made for the expansion with the exception of the Red Rock rally, which is the mountain road leading to the Red Rock observatory in the base game except the road is now dirt rather than pavement.
The gameplay focuses around the player becoming the Horizon Rally Champion similar to the base game's ambitions. To become the champion, the player must race in 6 rallies before unlocking the final rally to become the champion. Each rally earns the player a maximum of 60 points per rally (for first place), with 310 points needed to unlock the final.
Each rally contains 4 stages that the player must race. There are no other racers on the track (unlike real rallying where the starts are staggered to give the illusion of no other racers) and must race against times set by other AI drivers. The times are compared during mid-race checkpoints that indicate race position as of that checkpoint and split times. There are approximately 4 or 5 checkpoints per stage, although it depends on the length of the stage. At the end of each stage, the times are added to an overall total for that rally. The best time at the end of the 4 stages (and hence the rally) wins the rally; thus this expansion tests the player to perform well across all four stages to win the rally.
The game also adds in 2 new playlists for the multiplayer section of Forza Horizon: Social Rally and Veteran Rally. These two playlists offer similar experiences to Social Racing and Veteran Racing except on the new rally stages rather than Festival Events. The playlists each cycle between the fourth and final stage of each of the rallies and never includes the 3 composite stages of the final stage.
Custom games can also be created with the Rally expansion, and using the settings, the composite stages (1 through 3) for each rally can be played online.