Is the Toyota Urban Cruiser Taisor's fuel efficiency claims realistic in the real world?

The Urban Cruiser Taisor comes with impressive fuel efficiency figures according to Toyota, with the 1.2L petrol offering 21.71 kmpl and the 1.0L turbo petrol promising 22.8 kmpl. With rising fuel prices these numbers are quite attractive. But often we find a huge gap between the claimed fuel economy numbers and the actual fuel economy. Actual mileage is affected immensely by driving style, the types of traffic, and climate because of which a car consumes more fuel when it is driven on traffic jams, bumpy roads, or climbs uphills. Some owners report getting close to the claimed figures, and others report much lower efficiency. The discussion also includes fuel economy among the different engine options (1.2L NA, 1.0L Turbo, and CNG) in different driving conditions. The question here is how does the Taisor fare in real world fuel efficiency, do the claimed figures hold up in everyday driving or are they just overly optimistic marketing numbers?