Thanks all. As noted I've only had the car for a week or so. CEL has not come back on and I have had zero shift problems since, despite equally cold morning starts. I've now been through the records (from original purchase to date) and find no references to any shifting or transmission problems but also no indication of transmission service. Will probably have the local MB dealer do transmission service this once just to get off on the right foot with this car. I'll be going through things under the hood when I get into the WVO conversion. Might rebuild the driver's seat and add a seat heater first, though. Heated seats and adjustable lumber support in the Passat have spoiled me!