Can I make cars using auto-desk inventor because I know mostly how to use inventor but i have no idea how to make them in blender?
if it can be separated into pieces(hood, front left fender, front right fender, trunk. etc..) and then saved as a .dae(collada) then yes, you can use inventor
Generally it is possible - but it is not recommended at all. Inventor is a CAD program, the modeling process therefore is different to programs like Blender or 3ds Max (Volumina vs. Surfaces). Converting an Inventor model into a format BeamNG can read will reduce the quality of the mesh, coming along with many useless polygons. This means you would have to clean up your model - very time consuming, you could learn an appropriate program for game models in that time. You need Blender (or 3ds Max, better not Sketchup) for exporting and texturing anyways, so try to learn that.