Frost re-setting mileage trip?

First couple of frosty mornings since getting my Facelift TD4 Auto - and to my surprise the trip set itself to zero at start-up. Anyone else seen this? Maybe my battery is getting marginal and dipping volts too much on starting a freezing cold engine. Labours a bit on the starter but does start OK

I'd say you are correct, my battery died in the cold and I had the same first symptom

That'll be the battery. Mine did it for two winters, til the battery finally goosed. New battery has completely solved the problem.