So my 2013 Q3 tfsi has 118k miles on the clock and fuel economy had dropped (over the last 3 years) from 34 to 30 mpg plus it was lumpy when cold and I had to drop it into 5th gear to go up an incline on the motorway.
My research suggested that the likely culprit was carbon buildup on the inlet ports and the only real cure was Walnut Blasting. Quick check showed that Dukes Park Automotive was the nearest place to offer this service (using Industry Standard- BMW approved - gear).
The quote was reasonable and I decided to include an (EDT) engine flush.
I left the car with them for 8 hours and drove 20 miles home then the following day I did an 80 mile round trip on various roads and then I checked the Trip Average MPG and it shows 37mpg . . . . Holy Moly I have never seen that figure before, the best average I ever got was 33.9mpg and that was from 2013 til 2018!