I got a really comprehensive reply from Mercedes-Benz US:
At this point in time Mercedes-Benz will not be offering the Viano Marco Polo Westfalia Van on the US Market in the immediate future.
Please be assured your comments and interest in this vehicle have been noted.
Importing a European (non-conforming) model is not recommended for some of the following reasons:
1. The dealer network is not trained nor obligated to service vehicle.
2. Parts are not stocked at local dealers, and would need to be ordered from Germany.
If you still wish to do so, under the Environmental Protection Agency (emission) regulations, before the car is brought into the U.S., the owner of the vehicle must contract an "Independent Commercial Importer" (ICI). This ICI would then file the proper paper work with the U.S. Customs and modify the vehicle to comply with U.S. EPA regulations upon import. In addition, under safety regulations promulgated by NHTSA, the owner must contract a "Registered Importer" (RI) to bring the vehicle into conformity with applicable Federal Motor Vehicle Safety standards (FMVSS). The ICI must be on the current Environmental Protection Agency (EPA) approved list of Independent Commercial Importers and the RI must be on the current National Highway Traffic Safety Administration approved list of Registered Importers. These lists are available from the EPA and NHTSA. Neither the EPA nor NHTSA recognize "modification" work performed outside their jurisdiction. The car must be modified in the United States.
Mercedes-Benz USA, LLC is not an "ICI' or an "RI" and, therefore under federal regulation, is not permitted to act as an "ICI" or "RI". The importer (owner) must deal directly with EPA, NHTSA, the ICI and the RI. The addresses of the two federal agencies are:
U.S. Environmental Protection Agency
Manufacturers Operations Division (6405J)
401 M St. SW
Washington D. C. 20460
telephone: (202) 564-9660
telephone for list of ICI: (202) 564-9250
telefax: (202) 564-9596
National Highway Traffic Safety Administration
Director of the Office of Vehicle Safety Compliance (NEF-32)
400 Seventh Street, SW
Washington, D.C. 20590
telephone: (202) 366-5313
telefax: (202) 366-1024
If you have any questions regarding this matter, or if we can be of any other assistance, please feel free to e-mail us again or call us at 1-800-FOR-MERCedes (1-800-367-6372).