I Recently went to collect a tdi Sport that was having sensoir problems and occasionally would cut out and the temperature of the engine was running at 60 (it was not the temp sensor because if I switched the climate off the temperature did start to rise. (a broken Thermostat and some Camshaft / crankshaft sensor problems were resolved).
But it meant me driving the car at a lower speed than normal, just in case.
It was basically all motorway driving at just over 60 MPH.
It averaged (according to the DIS) EIGHTY MPG on the 64 mile trip.
The same journey back, but this time at 75 on the speedo (i.e. around 70 true MPH) and it averaged just over 60MPG on the same roads and distance.
Even bearing in mind that the DIS is not completely accurate (but it is more than close enough) that is pretty much spot on.
I am impressed with 60 MPG at 75 and really impressed with 80MPG at 60ish.
Take off a small percentage for the DIS variances and some very modern cars would find it difficult to match those figures and with such a torquey little engine too.
Steve B