Update: Early indications are good, and suggest he may have been right, unless something has just spontaneously resolved itself. I did a 40 mile round trip, mainly motorway, yesterday. The first 10 miles it was as previous days, with ridiculous fuel consumption. Then I started seeing much more typical readings in the 'live' MPG readout, and the average since start started to increase. By the end of the trip the average was just above 30mpg - double what I'd been seeing for similar journeys over the previous couple of days. If it has finished a regen and we start afresh today I'd expect to be seeing an average of mid-30s again in the coming days. I'm not quite ready to relax yet, but hopefully all will be well from here on.