My truck ran fine until it got down in the low 30's to teens, still ran good, but couldn't get it to go through the filter at much more than an idle. If I got down on the throttle, the fuel filter light would come on and the truck would stumble. It was very drivable, just couldn't get heavy on it or pull anything til the temps got above 30ish. Don't forget to switch tanks at anything below 35 without a block heater.
Cannot speak for the Mercedes, I just acquired all three of them this spring. Going by how well designed the preglow system is, and how well they start on pure WMO now, well its a 90/10 mix I'm thinking they will be less of a problem than the truck is. One good thing to know about the 722.*** Mercedes automatic is they can be pull started also, you have to follow the correct sequence. Before feeding them any WMO i verfied that they will roll start. You have to have a VERY big hill or pull them, but once they get up to around 40MPH with a cold transmission, or 30MPH with a hot transmission they will self start. You HAVE to follow the correct sequence. Place the car in park, key off, turn key fully on place transmision in N begin roll til up to 40MPH and quickly drop the sifter into it's lowest gear position. Book says not to pull it for more than one minute at a time if it fails to start immediatly.