Honda Ridgeline RTL MPG Gas Mileage Data. MPG Combined city hwy highway. This is the estimated average annual insurance premium being charged in your state. The premium .Following shows the average MPG of each of the vehicles in the system. Honda Ridgeline RTL E .L V GAS Automatic Speed Crew Cab Pickup Added Jul Fuel ups. Property of rickooten . . Avg MPG. Ridgeline. Honda Ridgeline Black Edition Added Apr .