People, average matters on how much you shift the gear, if you're constantly changing the gear even your speed is low the average will dropped. That is the reason in rushy/traffic areas the car average dropped because you're constantly changing the gears whereas on long you're using big gears mostly. Also, if a person office is 10 km far but there are a lot of turns and breakers as compared to a person whose office is 20KM far but its a straight road the second person will be getting way better average then the first one. Its proven and practically observed. Keeping the car around 2-3k RPM is very difficult but it surely helps in getting a perfect average. This car easily gives 13km-14km per litre with AC in traffic and without AC it gives upto 16KM per litre but with the condition mentioned above. Rest, many other things do matter like fuel quality, calculation method, road conditions, etc.