Forza games have a system of achievements, points and rewards.
Maximum number of points for each game:
FH4 3,000
FH3 3,000
FH2 3,000
F&F 500
FH1 3,000
FM7 3,000
FM6 3,000
APX 1,000
FM5 2,000
FM4 2,000
FM3 1,000
FM2 500
Total available points 25,000
Your tier is based upon the number of points you have achieved:
Tier 1 starts at 0
Tier 2 100
Tier 3 500
Tier 4 1,000
Tier 5 2,500
Tier 6 5,000
Tier 7 7,500
Tier 8 10,000
Tier 9 12,500
Tier 10 15,000
Tier 11 17,500
Tier 12 20,000
Tier 13 22,500
Your weekly rewards are based upon your tier:
Tier 2 25,000
Tier 3 50,000
Tier 4 75,000
Tier 5 100,000
Tier 6 125,000
Tier 7 150,000
Tier 8 200,000
Tier 9 250,000
Tier 10 300,000
Tier 11 350,000
Tier 12 425,000
Tier 13 500,000
List of achievements for FH4:
Car Masteries 50 (400)
Cars Owned 100 (250)
Days Played 50 (500)
Driver Level 100 (350)
Gamerscore 1,000 (500)
Horizon Story Chapters 15 (300)
Miles Driven 2,000 (350)
Properties Owned 10 (200)
Roads Discovered 300 (100)
Ultimate Passes 50 (50)
The first figure is the number to be achieved in the game, the second figure (in brackets) is the points which will be gained by completing the first figure.
For example if you play the game for 50 days, you will gain 500 points.
The Gamerscore figure is calculated from many individual achievements and the True Achievements site maintains good guides on Gamerscores. e.g.
There’s also the forum’s fairly extensive 120+ page FAQ on Tiers and Rewards:
https://forums.forza.net/turn10_postst262_Forza-Rewards-FAQ.aspx