The avg u r talkin abt is for the highway trip only ? Or it also includes dist covered with in a city?
I wud recommend that u chk ur cultus' fuel avg on highway thru manual method.... i.e get the fuel tank topped up before travelling on highway and reset trip meter, when highway trip finishes get the tank topped up again and divide the fuel litres filled in 2nd top up with trip meter's Kms....
Secondly, avg of 22-24 Kms per litre shud cm for speeds between 60-80 Kms/hour on a highway. You may be travelling at higher speeds....