I created a fun drawing back during AutoCAD 2007 to show off the mental ray rendering engine that had been added to AutoCAD 2007. Seeing the then updated rendering engine and the power and quality like its fellow Autodesk rendering engines in 3ds max was something to be shown.
When I showed it at one location in Asia people thought I was fooling them, but I showed them step by step and convinced them it was indeed AutoCAD rendering.
If you have a multi-core machine you can see the number of tiles being rendered match the number of cores.
I have since updated the drawing a wee bit and thought I would throw it out for download so that others can play with it.