Consider a vehicle with a 3-speed manual transmission. The corresponding fuel efficiency map of the engine is shown below. You are driving at a constant vehicle speed. The engine speed in each of the 3 gear settings is shown by the 3 red vertical lines. 3rd gear 2nd gear 1st gear 100 80 60 60 60 Engine power, kW 40 40 20 20 255 265 285 320 350 400 500 600 700 800 0 1000 2000 3000 Brake specific fuel consumption (BSFC) g/kWh 4000 Engine speed. rnm 5000 While driving at constant speed at 0% grade, the required tractive power is 20 kW (shown by a horizontal red line). In which gear should you be driving to maximize fuel efficiency?