Full list of all 50 Hitchhiker (Windows) achievements worth 2,500 gamerscore. It takes around 2-3 hours to unlock all of the achievements in the base game.
The base game contains 19 achievements worth 1,000 Gamerscore, and there are 3 DLC packs containing 31 achievements worth 1,500 Gamerscore.
Reach player level 20
Get in 100 vehicles
Complete 50 missions
Reach player level 15
Fail a mission when you are close to the end
Complete a mission with less than 5 seconds remaining
Complete 30 missions
Use 50 boosts
Use 50 u-turns
Use 10 overtakes
Reach the destination in a Police car
Get knocked over by an Ambulance
Complete 10 missions
Complete a mission while overtaking
Read the credits
Complete all tutorial missions
Get in 3 vehicles in a single mission
Complete a mission without getting out of a car
Complete the first mission
Complete 10 challenges
Use all of the power ups in a single mission
Complete your first challenge
Complete an extreme challenge
Level up by completing a challenge
Complete an extreme challenge with 30 seconds or more remaining
Access the city expansion
Earn a grade A rating by completing a time trial
Complete a time trial
Be the first car in the queue at a train crossing
Use a car, train and helicopter in the same mission
Walk around the park
Ride in a helicopter
See what the ducks have to say
Access all points of interest
Access a point of interest
Get off a train at the same station you got on after completing a lap of the track
Ride on a train
Access the old town expansion
Play the game at midnight
Ride in a helicopter during a thunder storm
Use a boost during a thunder storm
Complete 5 missions at night
Complete a mission with Eve
Complete 5 missions during the day
Complete a mission with "The Boss"
Complete a mission with Lola
Complete a mission with Carl
Complete a mission with Mia
Complete a mission in the rain
Complete a mission with Vincent