4 years, quite a few hours, never reset my computer in my A4, thought would be good info for people asking about economy. A4 TDI ultra, 2017, I live in Devon and drive mostly a and b roads, spirited driving. Was getting 52mpg until about 10k miles ago so something has changed on the car for it to drop down. Been a good 4 years. No faults, just quite a few michelins and brakes.