People says wrong, Civic manual hardly goes to 10km/ltr if you drive on lite foot.
I have civic 08 Prosmatec, gives me 8km maximum though i have original Honda Airfilter, Iridium Autolite high end plugs, throttle body and everything is upto date. Some times it goes to 9-9.5km/ltr.
My car is stock, no alloyrims yet, but planning to go for 17s but for sure it'll ruin the avg