Here is the full list of all 28 Roadkill achievements.
Destroy 10 enemy buzzkills.
Destroy 10 enemies driving the Frag Wagon.
Destroy 10 enemy Terraininators.
Destroy 10 enemy Buzzards.
Destroy 10 enemy DeathLoreans
Destroy 10 enemy Nightcrawlers.
Destroy 10 enemy Doom Buggies
Destroy 10 enemy Banshees.
Destroy 10 enemy SledgeRammers.
Destroy 10 Trikeceritops
Destroy 100 of each vehicle
Win a match on every map
Play Roadkill for 100 hours
Complete a match without dying
Kill 100 animals
Destroy 10 enemy Big Wheels.
Destroy 10 enemy Max Overkills.
Destroy 10 enemy Showdowns.
Destroy 10 enemy Thuggernaut Xs.
Destroy 10,000 enemy vehicles.
Destroy 25,000 enemy vehicles.
Win a match on Meltdown.
Win a match on Frostbite.
Win a match on Scorch.
Win a match on Airfield.
Win a match on Volcano.
Win a match on Arena.
Win a match on Doom Valley.