Apparently I have an Adblue tank buried somewhere under my spare tyre. Its amazing what you find out if you read your manual.
So does anyone have any idea of KMs travelled before it needs refilling.
So far, my V6 TDI is using a litre of Adblue every 400 miles (640 km) - the tank is 19.5 litres - in the UK, VW sell Adblue in 1.89 / 5.0 / 10.0 containers, the 1.89 screwing straight onto the filler but a hose, part # 000 012 499 is needed for the 5 / 10 litre containers, same part as used by Audi.
Adblue, an international standard specification, is available elsewhere - the containers don't fit the hose, but easy enough to get one VW container and then refill where-ever available.