Well...I've City 2005....and the best avg I got from it is about 17.5 KM/ Litre on the motorway driving at about 110.
However, a close friend of mine has 2007 City....and one day he offered me a ride on his car from Lahore to Islamabad. We filled up the gas tank at thokar and started our journey on the motorway...he kept the speed at 80 - 85 KM. It took us almost 5 hrs to reach isloo yet the avg we got was 22 KM/Ltr.
It was very boring and time consuming to keep this speed for five hrs. Yet the avg we got from the city was coool!