fabiorossi,
If you have not looked into Autodesk Showcase I would give it a try. It is really pretty straight forward. It will import FBX and dwg as well as many other engineering based formats. I have attached some of my more recent work using showcase. The Ram interiors and SLS have no post work done. The SRT8 Jeep has very little. These were not modeled in Sketchup (used Modo for most of it) although I wanted to show the capabilities of Showcase.
http://usa.autodesk.com/adsk/servlet/pc/index?id=6848305&siteID=123112
Scott