Driving

• Driving habits also help determine mileage. The weight added to the unit, such as passengers, full tanks and cargo, affects the mileage of the RV. The more weight you carry, the most gas you will use up.
  
  

Speed

• Find the speed that gives you the best mileage. This generally is between 55 and 65 miles per hour. Use your cruise control as much as possible.
  
  

Determine the Mileage of a Motorhome

• Determine your gas mileage by filling your tank completely before departing. Write down your mileage on the odometer at this point in time. Drive to your destination. When you reach your destination or have to stop for gas, fill your tank and write down how many gallons you purchase. Write down the odometer reading again. Subtract this from the original reading you wrote down. Finally divide this number by the amount of fuel you bought.