I was curious about this & started tracking it, below is mine. I know there are many variables in this like price of gas, miles driven, size of engine in vehicle, etc. Also, my wife used more than half of the gas i put in the truck except in Dec. & Jan. which are bad weather months for us.
Dec: Truck $97.42 Bike $40.18 = $137.60
Jan: Truck $132.10, Bike $27.13 = $159.23
Feb:Truck $56.00, Bike $69.52 = $125.52
Mar: Truck $54.25, Bike $51.30 = $105.55
Apr: Truck $65.25, Bike $80.76 = $146.01
May:Truck $15.00, Bike $70.52 = $85.52
Dec: Truck $97.42 Bike $40.18 = $137.60
Jan: Truck $132.10, Bike $27.13 = $159.23
Feb:Truck $56.00, Bike $69.52 = $125.52
Mar: Truck $54.25, Bike $51.30 = $105.55
Apr: Truck $65.25, Bike $80.76 = $146.01
May:Truck $15.00, Bike $70.52 = $85.52