Hi Gents just going through my first proper winter in the A6 and just thought I would highlight a couple of experiences, no problem starting at -6 degrees but unless you leave it for at least fifteen mins it takes an hour or so before you get red hot air, regens are far fewer as below +6 degrees the EGR won't open otherwise allied to the really cold air coming in the car would not run therefore less reburning of the exhaust gas, all seasons tyres are a must have not found any side roads with thick snow that I can't get in and out of and you can see where the extra money went, all in all very pleased, oh and usual strange noises from the discs first thing as the thousands of tons of road salt corrode the surfaces of the discs overnight also getting slightly less to the gallon as the extra cold intake charge of air can't atomise the fuel as efficiently, bigger fuel droplets don't burn as well.
Steve.