I've had to endure almost a week of mine going through an active regen
MPG figures fell of a cliff... my usual commute is a respectable 38 mpg for an urban 12 mile trip.... last week it it just got to 21 on most days.... two trips to pick up relatives down the M20 and I struggled to hit 32 mpg at around 65 mph plus I used half a tank of fuel per trip! (usually 49 to 51 mpg).
Only caught it once with the fans sounding like a jet engine but the ride was so jerky off throttle, like it was surging forward in traffic.
Up side exhaust note was very fruity.
Today and fingers crossed I think it's gone back to normal... trip into work and I was back to getting 39 mpg.