Got 15.3kmpl on meter and the same in manual calculation in a recent trip from isl to Lahore at 130 constant with cruise control and regular petrol with Econ mode on with 185/65r15 falken ze914 tyres inflated to 36psi in the front and 34psi in the back. I was also alone in the car with a bit of luggage, probably less than 40kgs of luggage. With 185 tyres the speed on the meter is almost exactly the same as GPS speed, at 130 on the meter, GPS speed is about 127-128kmh.
In Lahore my daily travel is through a rushy area and I usually get around 11.5kmpl with regular petrol and about 12.5kmpl with hi octane. In hi octane there's a difference between pumps, I find company operated total pump's hi octane to give the best mileage, pso is decent but feels a bit below total, hascol and shell hi octane feels the same as regular petrol.
I'm going to try full hi octane from isl to Lahore with the same constant 130 speed like above to see how much difference hi octane makes on the highway, but with my usual trips and usual driving with varying speeds on the motorway I've felt that hi octane doesn't make much difference on highway.
Compared to my other 2017 1.3 manual city I feel that in city in slow speed rushy areas, 1.5 CVT consumes more fuel, but it's about same in terms of efficiency in non rushy areas and it's a lot more fuel efficient on the highway. 1.3 manual due to top gear being a low 5th gear means that the car is at 4k rpm at 120 but 1.5 CVT is at around 2.5k rpm, makes a big difference in efficiency. With 1.3 manual getting above 12kmpl at any reasonable highway speed was basically impossible.
For hi octane I've always felt that the honda engines like higher octane than our regular petrol, every honda I've driven gets about 0.5 to 1 kmpl better efficiency with hi octane from a good pump. In comparison my old 2010 1.3 manual corolla got the same fuel efficiency with any fuel from any pump, the only difference I felt with better fuel was reduction in engine knocking.
Also old 1.3 manual had some knocking issues at low rpm with regular petrol, but 1.5 CVT with any fuel never gives any hearable knocking.