@matbooosh – When you convert to mesh, yes it does come in as a single mesh (block). Not sure if that's how the Cosmos system works, but you can still have access to the parts of the model. Not sure your level of C4D knowledge, but you will see triangles to the right of the mesh in the object manager after you convert to mesh. Each one of those is a group of polygons that are saved. Double-click one and you will see what each controls. Go down and try each one. You will see carefully selected polygons of the separate sections of the model. Assuming there is now way around the single mesh issue with Cosmos, there is not a one-click option for you to animate the car.
You will need to double-click the first Slection Tag. You will see the main body paint is now selected. If you right-click on the selection, you will find a command called Split. This will create a NEW object with JUST the body. The confusing part is notthing changes on screen, but in the object manager you will see a copy of your object with a .1 at the end. Now is a good time to name it correctly. The other annoying thing is all of the other materials and tags also come along for the ride, but are uncessary. The original mesh remains UNCHANGED. Now double-click on the next tag (or whatever part you actually need) and repeat the process. You will most likely need to further split some objects as I can see the all four rims are one, all four tires are one, etc... you should also recenter the axis on each part of the tires you need to animate. It's a pain, but you will get a nice multi-object car to animate.
When I began typing this long answer, I searched in case there was a faster way. I found this script somebody wrote that will do this in ONE CLICK, but can't get it to work.
--Edit--
It works! Here's the link with the proper file structure. I downloaded the incorrect file previously. Extract this ZIP to the Plugins folder in your C4D folder. I'm using r25 so I found it in the Extension menu at the bottom. Simply select your object with the selection tags and hit Selections To Objects 1.1 and give a few seconds to process. You now have a bunch of new objects. You still need to rename you objects and drop the materials back on each piece. Plus, if you want to animate a car's wheels, you will also need to separate the wheels. You could also select all the parts of the wheels including tires, rims, rotors, lug nuts. Go into Polygon mode and select everything EXCEPT one complete tire. Hit delete. Now you have one complete tire. You need to use the Axis Center command so when you rotate your tires, it doesn't use the old center point. Hope all this makes sense.
https://github.com/safina3d/c4d-selection2object/archive/refs/heads/master.zip
