Turbo prop engine simulation is simply, superficial, incomplete and flawed. No mixture effect, no governing, no propellar drag, etc… Thus you can not efficiently set engine RPM and cruise thrust. This results in constant high fuel consumption.
Keep in mind you need to double that number the fuel flow number you see is per engine. So your GPH is running 124 - 118. FL27, Torq 60%, conditioner lever at idle I manage 90 gph( 45 x 2 engines) TAS 291KT, GS 300