A few days back, I was struggling with the same issues. I was also getting the error code p0171.
The average I was getting was 9.5 km/l in the city and also on long, also the pick was very low.
I cleaned the fuel pump and also the fuel filter.
then I cleaned Cat, MAF sensor, and replaced Oxygen sensor 1 as it was not working.
After that now the average in the city is 16km/l and on long is 19km/l.