Can I use Fuelio with bi-fuel (LPG, CNG) or flex-fuel vehicles?

Yes. Fuelio supports bi-fuel vehicles. Open your vehicle (Menu → Vehicles on Android, More → Vehicles on iPhone) and switch on Bi-fuel vehicle (2 tanks), then pick the fuel for each tank, for example gasoline + LPG.

Once bi-fuel is switched on, you can choose the fuel subtype and the tank you are filling when adding a new fill-up.

Flex-fuel cars

If you drive a flex-fuel car that takes gasoline and ethanol in the same tank, don't use the bi-fuel option. Use the Flex setting instead. You'll be able to choose fill-up subtypes from the gasoline and ethanol groups.