I purchased XLI - Ecotec in October 2011.
it is giving me 260-75 KM per cylinder (Depends on CNG Pressure) within city area at the speed of 70-80 KM/H. So i will suggest u to go for Ecotec.
Its Petrol Average is 14.5 KM/L for local at speed of 70-80 KM/H, and 18.5 KM/L on motorway at speed of 80-90 KM/H