Thermodynamics

Chapter 9 | 535acceleration. Using cruise control on highway trips can help maintain a constantspeed and reduce fuel consumption. Steady driving is also safer, easieron the nerves, and better for the heart.Anticipate Traffic Ahead and Avoid TailgatingA driver can reduce fuel consumption by up to 10 percent by anticipatingtraffic conditions ahead and adjusting the speed accordingly, and avoidingtailgating and thus unnecessary braking and acceleration (Fig. 9–63). Accelerationsand decelerations waste fuel. Braking and abrupt stops can be minimized,for example, by not following too closely, and slowing down graduallyby releasing the gas pedal when approaching a red light, a stop sign, or slowtraffic. This relaxed driving style is safer, saves fuel and money, reduces pollution,reduces wear on the tires and brakes, and is appreciated by other drivers.Allowing sufficient time to reach the destination makes it easier to resistthe urge to tailgate.Avoid Sudden Acceleration and Sudden Braking(Except in Emergencies)Accelerate gradually and smoothly when passing other vehicles or mergingwith faster traffic. Pumping or hard pressing the accelerator pedal while drivingcauses the engine to switch to a “fuel enrichment mode” of operationthat wastes fuel. In city driving, nearly half of the engine power is used foracceleration. When accelerating with stick-shifts, the RPM of the engineshould be kept to a minimum. Braking wastes the mechanical energy producedby the engine and wears the brake pads.FIGURE 9–63Fuel consumption can be decreased byup to 10 percent by anticipating trafficconditions ahead and adjustingaccordingly.© Vol. 23/PhotoDiscAvoid Resting Feet on the Clutch or Brake Pedal while DrivingResting the left foot on the brake pedal increases the temperature of the brakecomponents, and thus reduces their effectiveness and service life while wastingfuel. Similarly, resting the left foot on the clutch pedal lessens the pressure onthe clutch pads, causing them to slip and wear prematurely, wasting fuel.Use Highest Gear (Overdrive) During Highway DrivingOverdrive improves fuel economy during highway driving by decreasing thevehicle’s engine speed (or RPM). The lower engine speed reduces fuel consumptionper unit time as well as engine wear. Therefore, overdrive (the fifthgear in cars with overdrive manual transmission) should be used as soon asthe vehicle’s speed is high enough.Turn the Engine Off Rather Than Letting It IdleUnnecessary idling during lengthy waits (such as waiting for someone or forservice at a drive-up window, being stuck in traffic, etc.) wastes fuel, pollutesthe air, and causes engine wear (more wear than driving) (Fig. 9–64). Therefore,the engine should be turned off rather than letting it idle. Idling formore than a minute consumes much more fuel than restarting the engine.Fuel consumption in the lines of drive-up windows and the pollution emittedcan be avoided altogether by simply parking the car and going inside.FIGURE 9–64Unnecessary idling during lengthywaits wastes fuel, costs money, andpollutes the air.