Great car to own and drive

i Bought Swift VDI in July 2008 and by now it has done over 3000 Kms. The car in all aspects is very good in its range. Before buying this i read lot of reviews and then finally decided to buy it.

As per the reviews i find only one concern as people said it gives mileage of around 17-18 km/litre but till now i am getting only 15 km/ltr in city(noida) and around 15.5 km/ltr on highway. When i went for First service the engineer told the car is fine and they could not do anything to improve the mileage as its all chip controlled.

Though if you get mileage of 15 in diesel thats good enough but if people are getting better mileage in VDI then i would defienetly be interested in knowing how they are getting. As far as my driving habits are very clean so i expected in Highway i should also get somewhere 18 km/ltr mileage which to my disappointment i am not getting.