It's just a guess, but maybe there are some issues with getting US DOT
approval for these imports.  I do know there are parts that have to be added
and removed at the VPC's at the US ports, so maybe there is a delay in
getting them ready for the new models.  Maybe it's just because Europe is
the "home" market for MBZ.

As for the engine size, MBZ is marketed as a luxury and performance brand in
the US.  This is why certain models never make it here and those that do are
generally not offered in some of the more economical engine choices
available in the rest of the world.  For example, the smallest engine
available in the E-class is the 3.2l V6 (soon to be replaced by the 3.5L
V6).  The US market just would not buy a European luxury car with the engine
performance  that of a Japanese economy car.  We like power and when we
spend two, three or even six times the price of an "average" car for a
"luxury" car, we want it to perform.

Models like the A-class range are not sold here because they would not be
seen as filling the need for luxury or performance.  However, we are
supposed to see the Compact Sport Tourer, which will be based on the
A-class, but it will likely be a much different vehicle in terms of luxury
and performance.  When the Sprinter was brought to the US, it was first
badged as a Freightliner, and then as a Dodge; never as MBZ.  Also, this is
not specific to MBZ.  VW does the same thing.  I have a cousin in Belgium
that owns a VW Golf that looks just like the US model, but its interior and
performance is much more "basic" than even our entry-level base model.

I guess a lot of this just has to do with what their market research
indicates that the US customers will buy.  Apparently Toyota, Honda and
Nissan realized that they would not sell as many luxury models if they were
branded with the same badge as their least expensive "basic transportation"
models, so they created Lexus, Acura and Infiniti.  Unfortunately, VW didn't
understand this and thus they have Phaetons sitting on dealer lots with no
buyers.  Really, who would by an $80K luxury car from the same company that
brought us the diesel Rabbit or the original Beetle?  Maybe MBZ could
transition itself in the US by realigning its luxury models to the Maybach
brand and keeping the Mercedes-Benz brand for more basic or "near-luxury"
models.  Or, maybe they need to just scrap everything currently sold under
the Chrysler brand and start introducing some decent "basic transportation"
under that brand (A-class, Vaneo, sprinter, etc.).