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The Car Talk guys addressed this and agreed with you. It's better to use the brakes to slow down since they're ablative and designed to be replaced with wear.

The Car Talk guys addressed this and agreed with you. It's better to use the brakes to slow down since they're ablative and designed to be replaced with wear. Causing the engine to do extra revolutions means extra wear on something that's quite difficult to replace/repair... That said, I drive a manual and use the engine for braking...

rsync 10y ago
I have always thought this. Growing up in the mountains, in Colorado, it was drilled incessantly into me how important it was to use engine/transmission braking on long hills, etc. I know it, I understand it ... and it always irked me. I never liked the idea that I would save wear and tear on a consumable that is meant to be regularly worn and repaired and instead transfer that wear and tear to an integral part of the car that is non-trivial to replace or repair. I would think very carefully about this if I were towing a boat or a horse trailer, but in a normal car it just seems backwards.
- corey_moncure 10y ago
  I believe the reasoning here is that braking all the way down a steep grade can cause your brakes to overheat and become temporarily inoperable. I don't know whether this is a real effect or not, but I have heard it given as a justification for engine-braking.
  - wvenable 10y ago
    This happened to a friend of mine driving through the rocky mountains in Canada; brake system overheated and he had no breaking ability until it cooled down.
  - deleted 10y ago
    [deleted]
  - Unklejoe 10y ago
    It's definitely a real thing. It's usually referred to as "brake fade" in car enthusiast communities. It’s usually more of an issue when racing, but it can happen if you have to do many hard stops during regular driving as well. I think it has to do with the pads releasing a gas when they get hot which creates a thin layer of “air” between the pad and the rotor. It's the reason that sports cars generally come with bigger brakes. Sure, a Toyota Corolla might be able to stop in a similar distance, but things change when you have to do it 5 times in a row. For most people, it’s not really an issue though.
  - giardini 10y ago
    unkeljoe: "braking all the way down a steep grade can cause your brakes to overheat and become temporarily inoperable. " That condition is known as brake fade/fading and occurs mostly with drum brakes and can occur on bicycles, motorbikes and automobiles. Braking heats the brake drums, which then expand. The drum may expand in diameter to the extent that the brake pads no longer contact the drum sufficiently enough to slow the vehicle. Your brakes "fade" away. Many vehicles have disc brakes in front and drums on the rear, an arrangement usually sufficient even in hilly country. Of course when pulling a boat or trailer having all disk brakes would be a safer bet. Brake drum fade is by far the most common manifestation, but there are other types of "fade", e.g., brake fluid can get heated up enought to boil and reduce braking system pressure, brake pads can "slip" more at extremely high temperatures: http://bicycles.stackexchange.com/questions/30449/do-mechanical-disc-brakes-suffer-from-heat-induced-fade http://bicycles.stackexchange.com/questions/30449/do-mechani... Last ditch efforts: shift into a lower gear, use any emergency brake (which is mechanical and bypasses the braking fluid system and so won't fade due to boiling fluid), and finally, use the inside of a hill/mountain as a giant brake pad by sliding your car's body into it as gently(!) as possible. Finally I feel compelled to warn anyone who ever pulls a trailer, boat or RV about a potentially fatal phenomenon they may encounter on even gently sloped roads: undamped driven harmonic oscillation between towed and towing vehicle. My first experience: VW Beetle towing a U-Haul trailer on a Pennsylvania turnpike mountainside. Traffic moderate in both directions. On a long downhill segment the trailer hitch began to move to-and-fro left and right, gently at first but, as I attempted to correct with steering, rapidly growing in amplitude. My steering reaction time and corrections were unfortunately timed precisely so as to _increase_ the amplitude of the oscillation. In a flash the rear end of the Beetle was hopping right and left! Insight - I need to dampen the oscillation. I gripped the steering wheel, braced both forearms against my legs and reduced all steering corrections to a minimum (I just kept the car on the road and in the proper lane). The car's front end skidded left and right as I kept the wheels as straight forward as possible. Then I slowly applied the brakes. This brought the oscillations under control and the speed down. I continued the trip at a much slower speed despite the honking of frustrated drivers behind me. That first experience, enhanced by both impending ignominious death on a mountainside and the sudden realization of the utility of my mathematical physics class* [1], was exhilarating. In the years since I have myself seen this occur several more times, which makes me think it must be a not-uncommon event that requires some warning. It once again occurred on IH 10 between Houston and New Orleans, one of the flattest pieces of land in the USA. A heavy-duty six-wheeler pickup was hauling a trailer full of goods on an extremely gentle slope at near 70-mph when his trailer hitch began to oscillate left and right. I had been following and observing his truck and noticed that the system seemed to be periodically oscillating, so I stayed well back and did not attempt to pass even on a four-lane highway. Finally things took a turn for the worse and, within 6 seconds of back-and-forth oscillation and attempts at correction, both truck and trailer were driven off the road into the grassy median. Luckily the median was wide flat grass and no harm occurred to driver, truck or trailer. I stopped and crossed the road as the driver took off his cowboy hat, waved it at his truck and trailer as if dismissing an unruly horse, bent his back, and put his hands on his knees in amazement. I spoke to him awhile, reassured him and gave as best an explanation to him of what I saw and what he might do to prevent further mishaps. He was quite out of sorts and I'm not certain he was fully able to absorb the lesson. He was definitely astonished to find himself on the median with his truck and trailer turned around 270 degrees from the direction he intended. Had this happened on a strip of highway without such a wide median the truck would have driven at ~60 mph into ongoing traffic at 70 mph. Had this happened on a hillside, I would estimate a 50% chance of both vehicle and trailer plummeting downhill. For these and other reasons, I think this phenomenon must kill more than a few people each year. More discussion of fish-tailing trailers: https://www.google.com/search?hl=en&source=hp&biw=&bih=&q=trailer+and+truck+oscillate https://www.google.com/search?hl=en&source=hp&biw=&bih=&q=tr... Physics can save your life: [1] http://hyperphysics.phy-astr.gsu.edu/hbase/oscdr2.html http://hyperphysics.phy-astr.gsu.edu/hbase/oscdr2.html - Under topic "Driven Oscillator Example" the red curve describes the ever-increasing amplitude experienced.
  - bnolsen 10y ago
    Oh yeah its real. Back 20 years ago I came down from Guenella Pass to Georgetown in Colorado and just about lost my brakes on those switchbacks just above Georgetown. One of the scariest situations I've been in.
- svdree 10y ago
  It's not about wear and tear. Brakes heat up when they're used, and descending an entire mountain on the brakes is likely to overheat them to the point where you have no braking power left at all. Not a good situation to be in on a steep slope. Using engine braking to keep your speed under control prevents this.
  - deleted 10y ago
    [deleted]
- hx87 10y ago
  Engine braking imposes negligible wear and tear on the engine. Instead of fuel-air explosions driving the pistons up and down, the pistons inefficiently compress and expand air at ambient temperature and pressure. Sure, extended use might take 100 miles of life off a 300,000 mile part, but are you really going to worry about that?
- kmonsen 10y ago
  The theory is if you go down a long mountain the brakes will be very hot when you are getting towards the bottom which means the performance is not as great. So if you then suddenly need the full power of the brakes it is not available anymore. Also if the mountain is tall enough the brakes might not make it all the way down which has happened a few times in Norway with catastrophic results for large vehicles like busses.
novaleaf 10y ago
i drive automatic, and I use engine braking. just turn off "overdrive", downshift to second, or first
alphapapa 10y ago
I just listened to Click and Clack a couple weeks ago, and a guy called in asking why his brakes caught on fire after he went down a long hill. Suffice to say that they do not recommend against engine braking--quite the contrary. Think about it: the engine is already spinning, so spinning it at a higher RPM for a few tens of seconds does no more wear than accelerating. The issue is not brake wear--the issue is brake fade, and potentially boiling your brake fluid! When you're going down a long hill, downshift and save your brakes! It could save your life!

rsync 10y ago

I have always thought this. Growing up in the mountains, in Colorado, it was drilled incessantly into me how important it was to use engine/transmission braking on long hills, etc. I know it, I understand it ... and it always irked me. I never liked the idea that I would save wear and tear on a consumable that is meant to be regularly worn and repaired and instead transfer that wear and tear to an integral part of the car that is non-trivial to replace or repair. I would think very carefully about this if I were towing a boat or a horse trailer, but in a normal car it just seems backwards.

corey_moncure 10y ago
I believe the reasoning here is that braking all the way down a steep grade can cause your brakes to overheat and become temporarily inoperable. I don't know whether this is a real effect or not, but I have heard it given as a justification for engine-braking.
- wvenable 10y ago
  This happened to a friend of mine driving through the rocky mountains in Canada; brake system overheated and he had no breaking ability until it cooled down.
- deleted 10y ago
  [deleted]
- Unklejoe 10y ago
  It's definitely a real thing. It's usually referred to as "brake fade" in car enthusiast communities. It’s usually more of an issue when racing, but it can happen if you have to do many hard stops during regular driving as well. I think it has to do with the pads releasing a gas when they get hot which creates a thin layer of “air” between the pad and the rotor. It's the reason that sports cars generally come with bigger brakes. Sure, a Toyota Corolla might be able to stop in a similar distance, but things change when you have to do it 5 times in a row. For most people, it’s not really an issue though.
- giardini 10y ago
  unkeljoe: "braking all the way down a steep grade can cause your brakes to overheat and become temporarily inoperable. " That condition is known as brake fade/fading and occurs mostly with drum brakes and can occur on bicycles, motorbikes and automobiles. Braking heats the brake drums, which then expand. The drum may expand in diameter to the extent that the brake pads no longer contact the drum sufficiently enough to slow the vehicle. Your brakes "fade" away. Many vehicles have disc brakes in front and drums on the rear, an arrangement usually sufficient even in hilly country. Of course when pulling a boat or trailer having all disk brakes would be a safer bet. Brake drum fade is by far the most common manifestation, but there are other types of "fade", e.g., brake fluid can get heated up enought to boil and reduce braking system pressure, brake pads can "slip" more at extremely high temperatures: http://bicycles.stackexchange.com/questions/30449/do-mechanical-disc-brakes-suffer-from-heat-induced-fade http://bicycles.stackexchange.com/questions/30449/do-mechani... Last ditch efforts: shift into a lower gear, use any emergency brake (which is mechanical and bypasses the braking fluid system and so won't fade due to boiling fluid), and finally, use the inside of a hill/mountain as a giant brake pad by sliding your car's body into it as gently(!) as possible. Finally I feel compelled to warn anyone who ever pulls a trailer, boat or RV about a potentially fatal phenomenon they may encounter on even gently sloped roads: undamped driven harmonic oscillation between towed and towing vehicle. My first experience: VW Beetle towing a U-Haul trailer on a Pennsylvania turnpike mountainside. Traffic moderate in both directions. On a long downhill segment the trailer hitch began to move to-and-fro left and right, gently at first but, as I attempted to correct with steering, rapidly growing in amplitude. My steering reaction time and corrections were unfortunately timed precisely so as to _increase_ the amplitude of the oscillation. In a flash the rear end of the Beetle was hopping right and left! Insight - I need to dampen the oscillation. I gripped the steering wheel, braced both forearms against my legs and reduced all steering corrections to a minimum (I just kept the car on the road and in the proper lane). The car's front end skidded left and right as I kept the wheels as straight forward as possible. Then I slowly applied the brakes. This brought the oscillations under control and the speed down. I continued the trip at a much slower speed despite the honking of frustrated drivers behind me. That first experience, enhanced by both impending ignominious death on a mountainside and the sudden realization of the utility of my mathematical physics class* [1], was exhilarating. In the years since I have myself seen this occur several more times, which makes me think it must be a not-uncommon event that requires some warning. It once again occurred on IH 10 between Houston and New Orleans, one of the flattest pieces of land in the USA. A heavy-duty six-wheeler pickup was hauling a trailer full of goods on an extremely gentle slope at near 70-mph when his trailer hitch began to oscillate left and right. I had been following and observing his truck and noticed that the system seemed to be periodically oscillating, so I stayed well back and did not attempt to pass even on a four-lane highway. Finally things took a turn for the worse and, within 6 seconds of back-and-forth oscillation and attempts at correction, both truck and trailer were driven off the road into the grassy median. Luckily the median was wide flat grass and no harm occurred to driver, truck or trailer. I stopped and crossed the road as the driver took off his cowboy hat, waved it at his truck and trailer as if dismissing an unruly horse, bent his back, and put his hands on his knees in amazement. I spoke to him awhile, reassured him and gave as best an explanation to him of what I saw and what he might do to prevent further mishaps. He was quite out of sorts and I'm not certain he was fully able to absorb the lesson. He was definitely astonished to find himself on the median with his truck and trailer turned around 270 degrees from the direction he intended. Had this happened on a strip of highway without such a wide median the truck would have driven at ~60 mph into ongoing traffic at 70 mph. Had this happened on a hillside, I would estimate a 50% chance of both vehicle and trailer plummeting downhill. For these and other reasons, I think this phenomenon must kill more than a few people each year. More discussion of fish-tailing trailers: https://www.google.com/search?hl=en&source=hp&biw=&bih=&q=trailer+and+truck+oscillate https://www.google.com/search?hl=en&source=hp&biw=&bih=&q=tr... Physics can save your life: [1] http://hyperphysics.phy-astr.gsu.edu/hbase/oscdr2.html http://hyperphysics.phy-astr.gsu.edu/hbase/oscdr2.html - Under topic "Driven Oscillator Example" the red curve describes the ever-increasing amplitude experienced.
- bnolsen 10y ago
  Oh yeah its real. Back 20 years ago I came down from Guenella Pass to Georgetown in Colorado and just about lost my brakes on those switchbacks just above Georgetown. One of the scariest situations I've been in.
svdree 10y ago
It's not about wear and tear. Brakes heat up when they're used, and descending an entire mountain on the brakes is likely to overheat them to the point where you have no braking power left at all. Not a good situation to be in on a steep slope. Using engine braking to keep your speed under control prevents this.
- deleted 10y ago
  [deleted]
hx87 10y ago
Engine braking imposes negligible wear and tear on the engine. Instead of fuel-air explosions driving the pistons up and down, the pistons inefficiently compress and expand air at ambient temperature and pressure. Sure, extended use might take 100 miles of life off a 300,000 mile part, but are you really going to worry about that?
kmonsen 10y ago
The theory is if you go down a long mountain the brakes will be very hot when you are getting towards the bottom which means the performance is not as great. So if you then suddenly need the full power of the brakes it is not available anymore. Also if the mountain is tall enough the brakes might not make it all the way down which has happened a few times in Norway with catastrophic results for large vehicles like busses.

novaleaf 10y ago

i drive automatic, and I use engine braking. just turn off "overdrive", downshift to second, or first

alphapapa 10y ago

I just listened to Click and Clack a couple weeks ago, and a guy called in asking why his brakes caught on fire after he went down a long hill. Suffice to say that they do not recommend against engine braking--quite the contrary. Think about it: the engine is already spinning, so spinning it at a higher RPM for a few tens of seconds does no more wear than accelerating. The issue is not brake wear--the issue is brake fade, and potentially boiling your brake fluid! When you're going down a long hill, downshift and save your brakes! It could save your life!