Bro
Eco mode doesnt do any wonders to milage, infact it makes the car heavy and curtails its pick and full potentia;
Try 90 - 120 kph without eco mode on and you should be getting same or around 23 KM / L Average easily
Eco mode is a compromise for no good reasons. It does give slightly better mileage but difference is not more than 1 - 1.5 km/L but compromise of quality drive is much bigger then this...