The fuel economy for a Class B motor home is typically between 18 to 25 miles per gallon on gasoline and 22 to 25 miles per gallon on diesel. By comparison, smaller Class C motor homes have a fuel economy between 10 and 15 miles per gallon.
Class B motor homes are the smallest variety of motor home. Manufacturers build Class B motor homes using a van chassis and an elevated roof. The dimensions of a Class B motor home are typically between 16 to 23 feet in length and 78 to 85 inches in width. As of 2011, the average Class B motor home costs between $40,000 and $60,000.