Interesting (to me) bit of trivia.
The 2011 and 2012 Sprinter owners manuals specifically caution about using fuel blends above B5. From 2013 onward it simply says dont use "bio-diesel" (among other fuels such as kerosene) without defining what is meant by bio-diesel.
In this undated brochure:
https://www.mbusa.com/vcm/MB/DigitalAssets/pdfmb/serviceandparts/biodiesel_Brochure5.pdf M-B states:
"Regular Ultra-Low Sulfur Diesel (ULSD) fuel meeting ASTM D975 can contain biodiesel up to 5%"
Then this:
"Only diesel with the ULSD label is approved (up to 5% biodiesel)". This is the standard green and white ULSD label.
And it states this:
"ULSD fuel meeting ASTM specification D7467 can contain biodiesel from 6% to 20%"
Then:
"B20 blends are generally not approved and should be only used on a very limited basis and only if unavoidable". This is a blue and black label.
It has been a year since I drove south (to NC, SC and Ga.) from New England but I had no trouble finding name brand (meaning names like Exxon, Shell, Sunoco) stations along the interstates selling what was labeled with the standard ULSD green/white label. We made our annual spring trip to the Outer Banks this past May and as usual didnt see any stations selling >B5 (per the pump labels). But then we werent looking at every station. Also, I usually stop at the same places each trip such as the service area station near the southern end of the NJTP and a Shell station on US158 in Barco, NC.
I too try to choose a station based on cleanliness and how busy they appear. And I avoid a station where the diesel pumps appear to be ancient pumps, filthy or overgrown and abandoned out back. Not just separate from the gas pumps, as often the separate island is placed for truckers and some places sell a lot of good fuel from these.
All that said, and knowing what I know now about the Sprinter and diesel fuel, I would probably avoid buying a vehicle with the new "clean" diesel technologies despite the superior fuel economy. In the US right now, it seems to be much less risky (from fuel selection to maintenance and repairs) to own and operate a gasoline engine powered vehicle.