Failed compiling 'PortableVehicles.cs':

1. 'IFuelSystem' does not contain a definition for 'fuelStorageInstance' and no accessible extension method 'fuelStorageInstance' accepting a first argument of type 'IFuelSystem' could be found (are you missing a using directive or an assembly reference?) [CS1061]
(PortableVehicles 39 line 329)

Failed compiling 'PortableVehicles.cs':
1. 'IFuelSystem' does not contain a definition for 'fuelStorageInstance' and no accessible extension method 'fuelStorageInstance' accepting a first argument of type 'IFuelSystem' could be found (are you missing a using directive or an assembly reference?) [CS1061]
(PortableVehicles 39 line 329)