To reduce the drag coefficient and thus improve the fuel efficiency of cars, the design of side rearview mirrors has changed dramatically in recent decades from asimple circular plate to a streamlined shape. Determine the amount of fuel and moneysaved per year as a result of replacing a 15-cm-diameter flat mirror by one with ahemispherical back. Assume the car is driven 25,000 km a year at an average speedof 95 km/hr. Take the density and price of gasoline to be 0.75 kg/L and $0.90/L, respectively; the heating value of gasoline to be 44,000 kJ/kg and the overall efficiencyof the engine to be 30 percent.