When I was working at NASA-Langley as a contractor, one of the other engineers in our group had worked for Open Road, based down somewhere near Disney World. The chassis they put their coaches on were driven from the Detroit area down to Florida from the auto plant. After the coach body was installed, they were test driven for a couple of hundred miles to find any manufacturing issues that driving them might uncover. After that they were driven to the dealer's location. My colleague drove several trips to the west coast while at Open Road
If the dealer was in Washington or northern Oregon, the rig could have had 5000 miles on it by the time the buyer saw it. It was my understanding that the chassis transportation and the trip to the dealer were done with the dashboard speedometer disconnected and a slave speedometer hooked to the cable, so that the one the customer saw had just a couple of hundred miles on it from the "works test driving".
I don't know if this still goes on, but, if I were buying new (fat chance!) I'd arrange to pick it up at the factory. At least then you know it only has the chassis delivery miles on it. Of course, if your Sprinter is really a Mercedes version, it could have the mileage from Stuttgart to wherever it went to be shipped to the US and from its port of entry to the RV manufacturer. More likely, it 's a Dodge-built or Freightliner-built chassis.