I'm trying to make a traffic simulation program with JOGL but I want to model the cars in 3ds Max or Blender but I'm not sure how to that. Any help will be appreciated.
There is an OBJ loader in JOGL itself and another one in JOGL-Utils. You can use an engine or a framework based on JOGL to load such models too: JMonkeyEngine, Unlicense-lib, JogAmp's Ardor3D Continuation, Java3D, LibGDX, ...
Look at SimpleObjExample and at this tutorial if you want something simple and working but using an engine based on JOGL rather than something lightweight.