How does the length of a car effect its gas mileage?

Question

How does the length of a car effect its gas mileage?

Answer 1

More car can add weight and increase drag

Answer 2

The length of the car really doesn't impact mileage.  Frontal area increases drag and uses more power to maintain speed.  Shape is far more important than length, since how air moves over the body will affect its coefficient of drag.  A car could be short like the Scion Xb, yet have a high frontal area, or long like a Bonneville Salt Flats racer and have very low frontal area.

Weight is separate from length, since you can have a long, light car or a short heavy one.  You don't address either of those variables, so you can't really say how length affects mileage.