gas mileage with a v10

Being able to estimate MPG is useful for trip planning but actual mpg depends on the speed driven on flat ground, amount of grades to be climbed, headwinds, tail winds, weight of vehicle and tire pressures, use of speed control and gears and engine performance. All class C's also have a lot of aerodynamic drag which increases dramatically with increase in speed. I would estimate 7-8 mpg for most rigs and be pleased with occasional higher actual mpg. Try to be accurate in computing miles driven vs gallons consumed and do it a number of times to come up with an average.