Full list of all 46 Forza Horizon 2 achievements worth 1,000 gamerscore. It takes around 60-80 hours to unlock all of the achievements on Xbox 360.
You beat them all to become Horizon Champion
You completed all 3 Road Trips
You collected 3 bounties
You smashed 25 Reward Boards
You made it to Montellino
You beat the train in a Horizon Showcase Event
You restored 5 Barn Finds
You made it to Saint Martin
You completed the Amateur Road Trip
You earned your first sponsorship bonus
You earned 10 Skill Points
Nice driving. You earned the Clean Racer Skill 100 times
You made it to Nice Massena
You earned the Blue Wristband
You made it to Sisteron
You made it to San Giovanni
You bought your first car
You made it to Castelletto
You won your first race
You earned the Yellow Wristband
You arrive at the Horizon Festival in style
Master your first Championship Event
Master all of the Events at 1 Destination
Master all of the Events at 3 Destinations
Master all of the Events at every Destination
Obtain the Purple Wristband
Obtain the Bronze Wristband
Obtain the Gold Wristband
Have 50 cars in your Garage
Have 20 million credits worth of cars in your Garage
Earn 109 Skill Points
Smash every Reward Board
Set a speed over 100mph at 20 different Speed Cameras
Complete 10 Bucket List Stunts
Complete all Bucket List Stunts
Earn a total of 1,000,000 Cr from Rivals
Join a Car Club
Drive down every road in the game
Compete in 20 Multiplayer Events
Compete in 200 Multiplayer Events
Complete an Online Road Trip Location
Complete 25 Online Road Trip Locations
Complete 25 Bucket List Stunts co-operatively
Join an Online Freeroam session with at least one friend
Complete 100 Playground Games
Earn every Sponsorship Bonus