Where can iI find what the letters and numbers mean? I have an E320, but just found out it is an E320w, but I don't know what that is. I also saw E320T in another place.

MB Model designations

All Mercedes models have a designation which identifies the vehicle chassis (i.e. W202, W203, W124, etc.). Try this link for a reference to some of the US Mercedes models:

http://fly.hiwaay.net/~gbf/mbmodels.html

You can also get some good information on the various models at the MBUSA site at:

MBUSA Models (http://www.mbusa.com/brand/container.jsp?/overview/overview_engine.jsp&yearModelCode=88_D300&class=88_E&rnav=024568&subNav=overview&menu=2_1&spec=2&category=0)