This case study follows a family’s dilemma about how to save money on gasoline. Should they keep their SUV and trade in their Corolla for a hybrid sedan? Going from 28 (Corolla) to 48 (Hybrid) miles per gallon (MPG) should really save money on gas. That’s a change of 20 MPG! Or, should they keep their Corolla and trade in their SUV for a minivan? The SUV gets about 13 MPG while the Minivan gets 17 MPG. Students learn how to analyze fuel efficiency in terms of “gallons per miles” driven instead of miles per gallon, and gain graphing and data analysis skills. An extension activity also relates fuel efficiency to greenhouse gas emissions. The case was developed for use in a high school general science course. It could be adapted for use in introductory physics, chemistry, algebra, or environmental science courses at the high school or college level.