FuelType POI is just a more complete gas stations database

Settings related to the type of fuel consumption of course use POI. They need POI to see if the type of fuel you use is present at that station (important for CNG/LPG/EV)
Calculations (average consumption) are done by the software - exe/apk and the corresponding ux

To be honest, I never use those options. I always plan the trip and before I start I check where to fill up the fuel.
Sometimes when I "go blind", I check on the way where the stations are and I roughly calculate where I need to refuel