Having owned a Sprinter for two years, I can make the folding comments:
We did have an LPG generator in ours. A few have diesel, but the bi=lk are propane
They drive nice, ride reasonably well, and you can go anywhere in town that a 1 ton pickup can.
They are expensive to maintain. For shop related shrives you can expect to pay $250 to $450 for an oil change (depending where and who does it), $1000 minimum for the first Schedule A servic=ve and $1500 or more for the Schedule B service. All parts for the MBS are expensive.
MB states not to idle in excess of 5 minutes due to complications with EGR setup
MB states not to use any biodiesel above 5% (although yo re now seeing some relief, I believe) If you run greater than 5%, you really have to watch your oil levels.
We really dislike the split bed design in our unit (rear bed slide) plus the chores of having make and unmake the bed every time you move.
Not a lot of room in the units if you hit bad e=weather and are confined to inside for several days. Also, storage, lack of, is a real issue as there is a limited cargo weight.
After two years, we went to a class A, and are very satisfied the upgrades space, and comfort.