The description is a bit misleading unfortunately.
It doesn't just require 4 different vehicles, but 4 different
TYPES of vehicles.
Like the achievement art suggests, I got this with a Mongoose, Warthog, Brute Chopper and Ghost.
But any combination of 4
DIFFERENT TYPES of vehicles will work.
The types, as far as I can currently tell, are:
Warthog:
- Warthog
- Razorback
- Rocket Warthog
Mongoose:
Chopper:
Ghost:
Tank:
Flying:
Turrets *:
- Shade Turret (Currently only found on the map Deadlock)
* (The comments suggest that using a Shade Turret counts as a vehicle, too. It's currently unclear if thats a bug or intended, but it could make things a bit easier)You have to drive 4 vehicles from different types in a single match to unlock the achievement.
Big Team Battle seems to be the only mode to get this in so far.
Warthogs and Mongooses can be found from the start.
For the rest you need to keep an eye out during the match.
At certain points of the match there will be announcements like "Ground vehicle delivery confirmed."
A couple seconds after a Pelican will show up on each teams side of the map and drop a Ghost, a Brute Chopper, a Tank, or a flying vehicle for each team.
Try to get them when they spawn in your base, as the action is mostly elsewhere, closer to the center of the map.