First, go to Computer, Click on the Drive Rigs of Rods is installed on, Next, Go into Program Files, Then locate your Rigs of Rods installation folder and scroll till you see OgreXMLConverter, Put the mesh fill you want to add to blender into OgreXMLConverter 2 files will pop out were the original file was located, Open Blender go to files and select import Ogre(.mesh.xml) locate the XMl file that came out of the converter (not the text file you can delete that) and select it and hit Import Ogre. I hope this helps you!