I have an Audi A4 1.9 tdi sport estate. It does 47 mpg on motorway runs...Not bad, but I was hoping it would be a little better. I do 75- 80 mph all the time and accelerate gently. What can affect the MPG? (Apart from the obvious ones like tyre pressure, poor running, etc.) It runs smoothly with no fault codes or known faults....Could the MAF or MAP cause this without symptoms??? The coolant sensor was recently changed for one off ebay and the thermostat was changed too....it now sits at 90 degrees most of the time.