Here is the full list of all 27 Zombieland: Double Tap - there are Road Trip achievements.
Beat a level with 4 players, each playing a main character
Beat the first level
Beat the second level
Beat the third level
Beat the fourth level
Beat the fifth level
Beat the sixth level
Beat the seventh level
Beat the eighth level
Beat the ninth level
Beat the tenth level
Beat all the side missions
Travel from L.A. to D.C. in under 5 hours and 45 minutes
Earn ZKOTW 12 times
Fully upgrade Weapon Damage
Fully upgrade Weapon Durability
Fully upgrade Health
Fully upgrade Speed
Fully upgrade Special Meter
Earn a kill with every weapon
Kill one of every zombie
Gain a kill with every environmental hazard
Last 88 minutes in a single Horde Mode
Kill three zombies with one sniper rifle shot
Kill four zombies with one shotgun blast
Kill six zombies and light yourself on fire with a single Molotov
Collect 100 Twinkies to celebrate 100 years of Hostess!