LPG fuel costs are insane

‌I drive a 5-year-old Sonata LPG. This month, I drove 850km, with about 800km of that being on the highway.
The Michael app showed 14.95 km/L and the MyHyundai app showed 15.1 km/L..
If converted to gasoline costs—since gas is on average 1.6 times the price of LPG—the fuel efficiency is equivalent to 24 km per liter..
I don't even drive on the highway that much....
In my previous Avante, I had to drive very economically (100–110 km/h) to barely reach 16.5 km/L, but this one hits this level even without hypermiling..
Of course, city driving is relatively minimal, but even so, it's about 20% better than the Avante when converted.