Old thread but I would like to share my experience of GLi 2020 manual variant. It gives 11-12 in moderate traffic of city like Lahore and gives 16-16.5KM/L on highway or motorway drive at 100KM/h Speed. Tested many times from tank to tank.
If your Gli manual is maintained, it should easily give 16 or close to 16 average.
Whereas, Altis X 1.6 with inefficient 4 speed auto transmission, hardly gives 10 on moderate traffic in city. You get 16 easily on 100 speed on motorway or highway.
Car should be properly maintained:
1- OEM oil+air filter.
2- Lowest possible oil grade for engine oil as per manual. 3- Plugs cleaning or changing at specified time and Throttle body cleaned if it has carbon deposit.
4- Proper tyre pressure, with balancing and alignment is done.