It's my understanding that the underlying engine in SolidWorks has been Mental Ray (for about a decade), yet the implementation of the interface in SolidWorks is so bad to this very day that it is easily worth paying up to $1K for a plug-in renderer like Hypershot, VRay, or one of the newer commercial offerings, if you are doing commercial work where time is money, and quality cannot be compromised. I've also used Mental Ray in XSI, and the complexity is pretty high, and necessarily so due to the need to enable features used for moving, deformable objects in an animation, special effects used primarily in movies, and so on. The power is there, but the ease of use wasn't, as of a year or two ago. My personal preference is something like Podium or Hypershot that does much of the work for you, taking away confusing options in the process, while still enabling renders as good as, or likely better than you could obtain in Solidworks' MR-based renderer (PhotoDoesn'tWorks) after hours and hours of PAIN.
Yeah, as noted already, I'm sure they left off Max because no one would use the native renderer for product design renders, especially when it ships with MR included.