You've heard wrong.
Firstly, it depends on driving habits.
Secondly, transmission also plays a major roll.
I have both Manual and Automatic Civics, both happen to be VTi versions, both 2005 manufactured.
From my personal experience over the years, I can tell you that on normal driving in Karachi with the usual stop and go traffic, my manual car gives me 10km/l and the Auto gives 8km/l.
If I drive with a heavy pedal, the manual gives around 8km/l and the Auto goes down to 6km/l due to the 4 speed transmission which I'm not a fan of.
Both my cars are VERY well maintained and have been giving me this mileage since the day they came out of the showrooms.
On highway it's a different story, I've managed to pull 14-15km/l easily out of my manual car and 12km/l from my auto.
I'd prefer if you get a manual VTi in good mechanical condition.
EXi won't give you any better mileage, especially the auto EXi.