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I am looking to conserve energy and increase brake pad life in the following scenario - Say I need to stop 500 meters from where I am at. Assume I am a very aware and an expert driver and that there is no other car behind me.

If I am driving at a speed of 70 kmph, which one of these will be the most effective ways to brake an automatic 2013 Camry :

  • A) Slow and steady brake (which will include the slight engine brake that engages with constant decelaration) till the stop line.
  • B) One swift braking action bringing the speed down to 50 and letting the car roll and finally bring it to stop with one swift brake.
  • C) Applying (sudden and full?)brakes only when near the red light (and legally stopping behind the stop line).

Or is there another way of braking that will do the least wear and tear on the car ? Till date I have used A) but I am interested to know of better ways to brake even if it prolongs the life of the brakes even by 1%

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    The physics of the situation imply that the answer is the one that minimizes the amount of energy that your brakes must absorb (which is essentially converted into heat and lost). Which means 'B' is the correct answer if you want to reduce the wear on your brakes. Options 'A' and 'C' are nearly the same, although 'C' may come out slightly ahead of 'A' in that sometimes the light may turn green before you need to stop, in which case you don't have to brake at all. – aroth Feb 11 '16 at 5:42
  • I'm concerned your question will be closed as a driving technique question. Perhaps you should edit it and focus on energy conservation and brake pad life. – DucatiKiller Feb 11 '16 at 6:11
  • @aroth isn't the energy the same in each situation (if we take away the engine/surface braking)? The key difference here would be how quickly kinetic energy is converted, as that would determine how hot the brakes get because of insufficient time for cooling down. I would go with A. – I have no idea what I'm doing Feb 11 '16 at 8:12
  • @IhavenoideawhatI'mdoing - The total amount of energy? Yes, that's the same. But it doesn't end up in the same place. In 'A' and 'C', basically all of the energy goes into/through the brake pads. In 'B', some (the first 20km/h of deceleration) of the energy goes into/through the brake pads. The rest is dissipated through other means, such as wind resistance (energy into the car's body and the surrounding air), the car's rolling resistance (energy into the axles, wheels, and road surface), etc.. If you want to send less energy into your brake pads, 'B' is what does it. – aroth Feb 11 '16 at 8:21
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    @aroth rolling and wind resistance does work in each case, but it will do most work in the case of a longest braking distance. By pressing the brake two times swiftly you send a lot of energy in to the pads. Wouldn't be so sure about B, it depends on the distance rolled and final speed before final brake. – I have no idea what I'm doing Feb 11 '16 at 8:35
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I'd recommend option D) use the brakes as little as possible. This basically involves getting off the gas as soon as it becomes apparent that you may have to stop (ie, you see brake lights ahead) and letting speed gradually decay due to friction and air resistance. This might be what you had in mind for option C) if you actually meant taking your foot off the gas at 500m from the stop, coasting for 400m and gradually losing speed so that you would be going much slower when you finally applied the brakes for the final stop.

The sooner you can begin coasting the better. Said another way, if you know you'll have to stop ahead and you're still holding a steady speed, you're basically wasting gas for the purpose of increasing your brake wear.

Also, consider not using overdrive at lower speeds if your car allows that. It makes a big difference in my Ford truck, as locking out overdrive also makes the ECU much more aggressive about engine braking and cutting fuel to the injectors (based on looking at throttle position and fuel flow on a ScanGauge), which means less wear on the brakes. My wife's car (also a Ford) is already pretty aggressive about cutting fuel and downshifting as the car slows, so there's no real benefit to locking out overdrive there.

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