Collision Woes

So I'm trying to import objects from CityEngine, and I read up on how to calculate collision Models in BeamNG, and it says to rename the collision mesh to "Colmesh-1"...but I have a strange problem. When I generate the collision model, it creates multiple collision models instead..so I obviously cannot rename every mesh the same thing. How can I fix this? Here's a screenshot of what I mean:

 

That's good and all... But I use 3DSMax. >.< Well, I COULD use blender too... because I have yet to learn how to use either program. (I'm a n00b to 3D modeling...even though I took 2 years of CAD in highschool...we didn't use Blender or 3DS though)

Also, if you simply copy paste the mesh and make one of them a colmesh...doesn't that cause lag, since the colmesh is just as high poly as the normal mesh? Take note, I'll be importing hundreds of these buildings along with a road system (All in one combines mesh preferably though).

 

I'm pretty sure skiper said he narrowed down the cause of the AMD render bug to using one giant mesh and that splitting it up into smaller ones solved that. think of the AMD fans!

As for the colmesh, I really don't know. If you want a dev response LJFHutch would be the one to ask.