I've had my A4 2.5 tdi multitronic from new, with 138k miles on the clock. The car has been faultless, is serviced every 15k on Audi long service and the miles covered are virtually all motorway.
I have a 90 mile round commute to work and have normally averaged 40/43 mpg, but fairly recently the mileage had dropped to 35 mpg with no change in my driving style. Car was serviced in December, with all filters changed and no code faults were found.
I have also cleaned the MAF, with no change to MPG.
I've also noticed that upon firing the car up in the mornings, there is a small cloud of smoke from the exhausts which quickly goes, the car also feels very sluggish between 1000-2000k revs, seems to take an age to reach 90c temp and the climate control never gets hot or cold (dispite being recharged recently and no faults/leaks).
I would be really appreciate any suggestions. Thanks