Drove back up from Manchester to Edinburgh today. Got a respectable 52.7MPG. Two turns away from home the car started a regen. Revs at 1000 and stop start not functioning. Got home and switched the car off and the fans were still running. I'm amazed that during a 225 miles / 4 hour journey the best time it could find to regen is when your back on a normal city road and about to end your journey!
Me too. Been on an 80 mile round trip, with oil temps generally up in the 98 to 102C for the vast majority of the journey. I would imagine that the DPF got hot enough for plenty of passive regenning which could have emptied the system, yet the fans were blaring when I got home, despite the oil temp settling back down to 92C.
The question is then....does the fan continuation always signal the static continuation of an interrupted DPF regen, or perhaps after an extended motorway run, could the DPF be clear and the fan is kicking in purely to cool down the DPF to protect it from overheating after the car has stopped? I'd like to think that this is the case, otherwise it would seem that by design, despite perfect passive regen conditions, VW has set the car not to take advantage of the situation, but makes the car regen at set intervals or set loading thresholds. This could also explain stop-start being disabled - if the fans need to be blaring to cool the DPF when the car is static, there is probably no economy advantage in allowing the engine to switch off and have the fans blaring instead, therefore stop-start is disabled.
I can't at this point tell what my DTUK boxed mpg is until I fill up, but current gauge readings would seem to indicate that actual mpg isn't a million miles away from MFD indicated mpg. The gauge was reading exactly half a tank (from full) when I hit 245 miles done. From experience, 1/2 a tank indicated is a little more than 1/2 a tank consumed. I normally do about 225 miles on an indicated 1/2 tank to get an actual 43mpg. My educated guess on current actual mpg to 245 miles in, is around 46.8mpg, although that has been bolstered by my mid range run, so it will drop again as I do a week of commuting to finish the tank. The indicated mpg for the 2 x 40 mile legs was 51.3 outbound and 53.8 on the way back.