To reduce the drag coefficient and thus to improve the fuel efficiency, the frontal area of a car is to be reduced. Determine the amount of fuel and money saved per year as a result of reducing the frontal area from 18 to 15 ft². Assume the car is driven 12,000 mi a year at an average speed of 55 mi/h. Take the density and price of gasoline to be 50 lbm/ft³ and $3.10/gal, respectively; the density of air to be 0.075 lbm/ft³; the heating value of gasoline to be 20,000 Btu/lbm; and the overall efficiency of the engine to be 30 percent.