New DWG file format
It was AutoCAD R14 the last time Autodesk use release in the product name. Then they decided to use year. However, they actually still use RXX.X. If you type ACADVER in command line, then you will see AutoCAD 2013 is actually R19.0.
AutoCAD 2012 is R18.2, 2011 is R18.1, and 2010 is R18.0. AutoCAD has 3 years release update cycle. The number RXX is changed every 3 years. And when it changes, it means it use new file format.
You will not be able to open DWG from 2013 in AutoCAD 2012 or below. Unless you save it to older version.
If you’re still using old version of AutoCAD, it’s time to update your TrueView to 2013.
New import file format
In AutoCAD 2012, Autodesk added the ability to import many MCAD file format. From SolidWorks to CATIA. But it was quite funny that it can’t import Inventor files (ipt and iam) as it is an Autodesk product. Of course we can open it with Fusion then save it to DWG.
In 2013, finally you can import Inventor files directly to AutoCAD.
I also find that now we can import Google SketchUp file (.skp) to Inventor Fusion 2013. Not directly to AutoCAD, but at least to Fusion. As long as I remember it was not there in 2012. I need your help to confirm this because I already uninstalled my Fusion 2012.
I think these are nice addition. At least Fusion is bundled in AutoCAD installation. But it would be nicer to have it all in AutoCAD, right? Because they already have the file translator, I believe it can be done. Or probably next release?