May be it gets better after 5000 Km. Your driving habits do matter.
I'm an aggressive driver and seldom allow anyone to overtake. My 92 Nissan - 1.5 EFI, with wiring still not sorted out is giving me 10+ in city and 12 on highway.
So your car is supposed to do better. Btw, swift has the reputation of being a fuel guzzler, but 8kpl is still not acceptable.