As the tittle says, is around town driving as bad as some suggest with the Sprinter? Meaning relatively short duration drives like 5-20 mins. If so, is there an additive you can use to mitigate and negatives? I would imagine that making sure you get some decent distance long drives in helps in some manner, but why? I suspect it has to do with emissions and reaching some sort of threshold temperature to burn something off but I don't know. Anyone care to provide me some education on this topic?
Lots of previous discussion on and around this topic. Not 4x4 specific.
In short:
Newer sprinters have diesel particulate filters, which capture the soot that is in the exhaust. The soot gets burned off either by mileage or a trigger from a differential pressure sensor, by injecting extra fuel to elevate the exhaust gas temperature.
So, short runs create more soot as the engine temp may not fully warm up. Additionally, the burn off of soot, known as a "regen" can take in the 10-15 minute range and is interrupted by braking.
3 interrupted regens in a row will trigger a CEL and perhaps an unneeded trip to the dealer who can manually trigger a regen with his MB diagnostic equipment.
So, if you mainly drive in city with short trips, then take your vehicle out for an uninterrupted run on the highway for 20-30 minutes every other week. No additives will help.