Here is the full list of all 40 Roundabout achievements.
In "Destruction Derby", take out 8 cars.
Drove straight for Beth.
Unlocked the Traffic Coner.
Die 360 times.
Make a huge mistake.
Purchase something from The Chrome Dome.
Unlocked the Inflatiboat For Cars.
In "Death from Above", survive for 30 seconds.
In "Run Like Crazy", get 150 yards away.
Unlocked the Reverser Wheel.
Follow a lady into the big smoke.
Purchase some property.
In "Ball Bouncers", bounce the ball at least 12 times.
View the "How's Your Driving" screen outside of the DMV ride. Useful, isn't it?
Collect every star in a single ride.
Unlocked the Pickup Finder.
Unlocked the Multiplier Freezer.
Unlocked the Beary Nice Music Box.
Survive the Mountain Fair Demolition Derby without exploding.
Stand still for a minute of silence at The Memorial.
Honk your horn 500 times, then honk your horn 500 more.
Revolve over 53,596 times.
Aggressively warn a dozen pedestrians with the Trafffic Coner.
Purchase a pet eagle.
Complete your first eSports Speedrun Challenge.
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 "The Great Hunt", find 6 regions.
Reach a 35x multiplier.
Collect every Cash Stash.
Accomplish every Sick Jump.
Discover all of the horns.
Purchase every hat and paint job.
Collect every star in every ride.
Purchase every property.
Reach 100% completion on a mission.
Reach 100% completion for the entire game.
Complete an eSports Speedrun without exploding.
Drive the entire "classic" length of Desert Limo without crashing.