Let's think about how the efficiency of a car is reported. It is usually given in miles per gallon. That is a length per volume. And length/volume is 1/area. So

you can write the fuel efficiency for a car in terms of the inverse of some area. What is the value of this area (in mm2 – that's millimeters squared) for a car that gets 30 miles per gallon? [1 gallon is 3785 mL (1 mL=1 cm³) and 1 mile =1609 m] Could you give a physical interpretation of this area?