cos your driving style has differed? because you’ve done different driving? because you’re filling the neck of the fuel tank as well as the tank? because traffic is lighter? because the weather is better? because its warmer?
there’s nothing, at all, in science that could make your car more efficient with 98ron fuel. you may as well wear a bracelet with a magnet in
I hear what you’re saying and I’m sure you’ve got your petrochemical/combustion science correct.
However, as I said above, my commute has not changed in traffic density, distance or route. I don’t use the car at the weekends, we use another one.
I drove for 6 months on 95 ron and now 10 months on 98 ron. The mileage I’m getting is different.