I've heard that one person in the team made a map exporter for GTA V. We modify Mafia 2, recently we've been trying to find a way to expand the map. I had an idea of putting a model of a map onto a car model - *we can only import and export car models via Zmodeler 3. It worked, later I came up with a script that locks the car's physics so it behaves like a static object.
This is the result of it:
Unfortunately you can't add new collisions (you can use only the original one) and it seems to be buggy nevertheless - It would be possible to add new collisions if we had a program that opens this file - PREFAB_0.bin, it is saved in sds/cars/xxxx.sds
xxxx.sds is a game file that packs all files of one model - including its geometry, geometry of collisions and files such as PREFAB_0.bin that refer to collision materials, to textures etc.
the xxxx.sds can be extracted using the SDS Tool (available on the internet)
Decrypting PREFAB_0.bin could be a solution but it seems that a map exporter for 3d max for Mafia 2 is the only way to go, if we want to convert maps into Mafia 2 properly.
One thing is for sure - there are people who would be making maps for Mafia 2, if it were possible - I myself would dedicate my life to it!