The Rover M16 spark ignition engine has a swept volume of 2.0 liters and operates on the four-stroke cycle. When installed in the Rover 800, the operating point for a vehicle speed of 120 km/h (74.5 mph) corresponds to 3669 rpm and a torque of 71.85 Nm, for which the specific fuel consumption is 298 g/kWh. Calculate the bmep at this operating point, the arbitrary overall efficiency, and the fuel consumption (liters per 100 km). If the gravimetric air-fuel ratio is 20:1, calculate the volumetric efficiency of the engine, and comment on the value. The calorific value of the fuel is 43 MJ/kg, and its density is 795 kg/m3. Ambient conditions are 27C (81F) and 1.05 bar. Explain how both lean-burn engines and engines fitted with three-way catalysts obtain low exhaust emissions. What are the advantages and disadvantages of lean-burn operation?