Vehicle mileage

Gas mileage is the number of miles you travel for each gallon of gas you get (MPG) The larger the car/suv or truck, the less MPG you will get because it takes more energy to make it move.

Several things contribute to determining the gas mileage any vehicle will get. Some of the factors are...
- weight
- air resistance (ie, coefficient of drag as a factory design issue, plus added drag such as windows down vs. rolled up)
- rolling resistance (e.g., types of tires, tire pressure, internal drivetrain parasitics [ie, friction])
- added load (ie, passengers, groceries and other stuff)
- type of engine & it's efficiency (larger displacement & higher output engines tend to get lower fuel economy)
- driving styles (ie, racing to stops, 'riding the brakes')

Regarding a vehicle's weight, as a rule of thumb, as a vehicle gets heavier, it's fuel economy is reduced. It requires more force to overcome the inertia that keeps the car stationary. And this reality is repeated every time a heavy vehicle stops & then launches again from a stop.