Hyundai Motor India — regarding km/lit and functioning of turbocharger

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Bought creta sx (O) diesel.
It is not giving the mentioned km/lit. After driven 700 km, the km/lit is 14.
When cars with lower h. P and lower torque overtakes, when creta engiene rpm is 2000 or 2100, wish to know whether turbocharger is working or not.
When checked with the local dealer - company own outlet - told me to drive only 100 km to find the fuel consumption / lit. He also told me that the turbo is working well. But i differ to accept.
There must be a valid reason to find no required amount of surge is taking place when the engine rpm is 2000 or 2100. The turbo reached max at 1750 engine rpm and be at the max up to 2750 rpm then declines as per details available.
Advice me.