Here is the full list of all 40 Roundabout achievements.
Unlocked the Traffic Coner.
In "Run Like Crazy", get 150 yards away.
In "Ball Bouncers", bounce the ball at least 12 times.
Drove straight for Beth.
Make a huge mistake.
Unlocked the Inflatiboat For Cars.
Stand still for a minute of silence at The Memorial.
Follow a lady into the big smoke.
Purchase something from The Chrome Dome.
Purchase some property.
View the "How's Your Driving" screen outside of the DMV ride. Useful, isn't it?
Collect every star in a single ride.
Collect every Cash Stash.
Discover all of the horns.
Accomplish every Sick Jump.
Purchase every hat and paint job.
Purchase every property.
Honk your horn 500 times, then honk your horn 500 more.
Aggressively warn a dozen pedestrians with the Trafffic Coner.
Reach a 35x multiplier.
Unlocked the Beary Nice Music Box.
In "Death from Above", survive for 30 seconds.
Unlocked the Pickup Finder.
Complete your first eSports Speedrun Challenge.
Die 360 times.
Purchase a pet eagle.
Unlocked the Reverser Wheel.
Reach 100% completion on a mission.
Unlocked the Multiplier Freezer.
Survive the Mountain Fair Demolition Derby without exploding.
Revolve over 53,596 times.
Get a better eSports Speedrun Time than the No Goblin team.
In "Limocide", take out 50 pedestrians.
In "Farming Simulator 1977", complete your farming in under 40 seconds.
In "Destruction Derby", take out 8 cars.
In "The Great Hunt", find 6 regions.
Collect every star in every ride.
Reach 100% completion for the entire game.
Complete an eSports Speedrun without exploding.
Drive the entire "classic" length of Desert Limo without crashing.