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It was completely frowned upon in my driving education (around 7 years ago) - and my driving school was/is the most popular in the UK. I always do a combinatio

It was completely frowned upon in my driving education (around 7 years ago) - and my driving school was/is the most popular in the UK. I always do a combination of down-shifting and braking as this saves fuel vs purely engine braking and I'm using my brakes what they were designed for; and you don't ever want to try emergency braking with cold brakes.

k00pa 14y ago
Something wrong with your driving education then...
- prawks 14y ago
  It's pretty simple to see that traditional braking triggers brake lights, while engine braking does not. Brake lights are there for safely, to prevent rear-ends. I'd be shocked if any driving education program encouraged engine braking. On a slightly different note, if your rev-matching isn't smooth when you downshift to engine brake, you're just using your clutch to slow the car, which is a much more expensive part to replace than brake pads/rotors.
  - X-Istence 14y ago
    In most cases when it is appropriate to use engine braking the person behind you has to already start matching your speed. In situations where you have to brake suddenly and quickly brake lights can warn the other driver, but in most cases when you are downshifting to engine brake you are slowing down slowly enough that the person behind you can make proper adjustments simply based upon the fact that they are now getting closer to you. It's a human PID loop! As for rev matching, yes, completely agreed, if you can't rev match your down shifts then engine braking is indeed going to use your clutch and that is more expensive to replace. However, if you are driving a stick shift car and you don't know how to properly rev-match on downshifts how will you easily get up the mountain where shifting from fifth to fourth to third is sometimes required simply to keep up with traffic properly? I can go from fifth at 3k to fourth at 5k without issues. Rev-matching in a stick shift is very important outside of the engine braking use case.
  - simias 14y ago
    During my driving course they always told me to apply the brakes, if only very lightly, while downshifting. This way the brake lights are there to warn people behind you. I always do it (even on motorbikes with the rear brake). I thought it was pretty standard.
    - prawks 14y ago
      That's pretty cool, they basically taught you heal-and-toe!
- jrabone 14y ago
  It's standard dogma, including in the advanced driving courses (eg. police). "Gears for go, brakes for slow" Why this is so, I'm not entirely sure; it does mean that you can change from manual to auto transmission without thinking (and potentially without making a fatal mistake at speed if you are pursuing a suspect). However, it just shifts the cognitive effort of making sure you're always in the correct gear (which I think is also standard advice in eg. the roadcraft system). From a professional owner / driver perspective (eg. a taxi), the answer is simple; brakes are cheap to replace, clutches aren't. What they really don't tell you about are things like left foot braking (which I don't do) and heel-and-toe (which I do, especially when leaving motorways where we tend to have a junction followed by an uphill slip road).
  - X-Istence 14y ago
    Moving from an manual to an automatic can still be quite jarring, even if you don't have engine braking. Ever been in an automatic after driving a stick shift for years? The brake pedal is twice as wide and is in approximately the same location as where the clutch is found ... get into an emergency situation? Your mind will automatically want to disengage the clutch and hit the brakes, so you go for where the clutch pedal would be normally and instead hit the brake pedal ... Yeah, I was used to driving my Subaru Impreza with a stick shift, then I drove my dads BMW 5-series, got into a sticky situation in traffic and had to come to a quick and sudden stop, there was no thinking involved, push the clutch and the brake was my immediate reaction... let me tell you, that BMW stopped on a dime, luckily there was no-one behind me or I'd have to explain to my dad how instinct and sheer muscle memory on my part caused someone to rear-end me and ruin his car, all because my left foot went for the clutch and caught the edge of the brake pedal...
    - simias 14y ago
      Some automatic cars even put the parking brake on a pedal close to where the clutch is on manual. It's quite... surprising when you're used to drive stick.
      - X-Istence 14y ago
TylerE 14y ago
You're more or less totally wrong, in a modern car. Under overrun conditions (e.g. engine braking - driveshaft turning the engine, essentially), a modern engine totally shuts off fueling completely, so engine braking alone is always a MPG win, as zero fuel consumption is less than idle fuel consumption with the clutch in. Also, brakes these days are so good that you really NEED anti-lock. The limiting factor in stopping is the grip of the tire.
- jamesjguthrie 14y ago
  Yeah, in perfect conditions (i.e. unlimited stopping distance) with perfectly matched revs when downshifting you will save fuel. In the real world, just brake.
  - jamesjguthrie 14y ago
    Note: perfectly matching revs while downshifting isn't using your gears to slow; it's just slowing.
  - X-Istence 14y ago
    Why not a combination of both? Use the engine to slow the car down for the first part, and then use your brakes?
  - georgefox 14y ago
    I'm not sure I understand why your revs would need to be perfectly matched to avoid fuel consumption. If you're slipping the clutch, you're wearing the clutch, but what does that have to do with fuel consumption? Personally, I wouldn't downshift without a rev match because of the clutch slip factor, but I was always under the impression that with the throttle closed and the engine being driven by the wheels (not by the throttle via idle), you were using virtually no fuel.
    - jamesjguthrie 14y ago
      If you don't rev match then when you down shift your revs will be higher and as such you'll be fuelling again without having to touch the throttle with your foot.
georgefox 14y ago
> I always do a combination of down-shifting and braking as this saves fuel vs purely engine braking... Assuming your car is reasonably recent, engine braking doesn't use significant fuel. See http://en.wikipedia.org/wiki/Engine_braking#Legal_implications http://en.wikipedia.org/wiki/Engine_braking#Legal_implicatio....

k00pa 14y ago

Something wrong with your driving education then...

prawks 14y ago
It's pretty simple to see that traditional braking triggers brake lights, while engine braking does not. Brake lights are there for safely, to prevent rear-ends. I'd be shocked if any driving education program encouraged engine braking. On a slightly different note, if your rev-matching isn't smooth when you downshift to engine brake, you're just using your clutch to slow the car, which is a much more expensive part to replace than brake pads/rotors.
- X-Istence 14y ago
  In most cases when it is appropriate to use engine braking the person behind you has to already start matching your speed. In situations where you have to brake suddenly and quickly brake lights can warn the other driver, but in most cases when you are downshifting to engine brake you are slowing down slowly enough that the person behind you can make proper adjustments simply based upon the fact that they are now getting closer to you. It's a human PID loop! As for rev matching, yes, completely agreed, if you can't rev match your down shifts then engine braking is indeed going to use your clutch and that is more expensive to replace. However, if you are driving a stick shift car and you don't know how to properly rev-match on downshifts how will you easily get up the mountain where shifting from fifth to fourth to third is sometimes required simply to keep up with traffic properly? I can go from fifth at 3k to fourth at 5k without issues. Rev-matching in a stick shift is very important outside of the engine braking use case.
- simias 14y ago
  During my driving course they always told me to apply the brakes, if only very lightly, while downshifting. This way the brake lights are there to warn people behind you. I always do it (even on motorbikes with the rear brake). I thought it was pretty standard.
  - prawks 14y ago
    That's pretty cool, they basically taught you heal-and-toe!
jrabone 14y ago
It's standard dogma, including in the advanced driving courses (eg. police). "Gears for go, brakes for slow" Why this is so, I'm not entirely sure; it does mean that you can change from manual to auto transmission without thinking (and potentially without making a fatal mistake at speed if you are pursuing a suspect). However, it just shifts the cognitive effort of making sure you're always in the correct gear (which I think is also standard advice in eg. the roadcraft system). From a professional owner / driver perspective (eg. a taxi), the answer is simple; brakes are cheap to replace, clutches aren't. What they really don't tell you about are things like left foot braking (which I don't do) and heel-and-toe (which I do, especially when leaving motorways where we tend to have a junction followed by an uphill slip road).
- X-Istence 14y ago
  Moving from an manual to an automatic can still be quite jarring, even if you don't have engine braking. Ever been in an automatic after driving a stick shift for years? The brake pedal is twice as wide and is in approximately the same location as where the clutch is found ... get into an emergency situation? Your mind will automatically want to disengage the clutch and hit the brakes, so you go for where the clutch pedal would be normally and instead hit the brake pedal ... Yeah, I was used to driving my Subaru Impreza with a stick shift, then I drove my dads BMW 5-series, got into a sticky situation in traffic and had to come to a quick and sudden stop, there was no thinking involved, push the clutch and the brake was my immediate reaction... let me tell you, that BMW stopped on a dime, luckily there was no-one behind me or I'd have to explain to my dad how instinct and sheer muscle memory on my part caused someone to rear-end me and ruin his car, all because my left foot went for the clutch and caught the edge of the brake pedal...
  - simias 14y ago
    Some automatic cars even put the parking brake on a pedal close to where the clutch is on manual. It's quite... surprising when you're used to drive stick.
    - X-Istence 14y ago

TylerE 14y ago

You're more or less totally wrong, in a modern car. Under overrun conditions (e.g. engine braking - driveshaft turning the engine, essentially), a modern engine totally shuts off fueling completely, so engine braking alone is always a MPG win, as zero fuel consumption is less than idle fuel consumption with the clutch in. Also, brakes these days are so good that you really NEED anti-lock. The limiting factor in stopping is the grip of the tire.

jamesjguthrie 14y ago
Yeah, in perfect conditions (i.e. unlimited stopping distance) with perfectly matched revs when downshifting you will save fuel. In the real world, just brake.
- jamesjguthrie 14y ago
  Note: perfectly matching revs while downshifting isn't using your gears to slow; it's just slowing.
- X-Istence 14y ago
  Why not a combination of both? Use the engine to slow the car down for the first part, and then use your brakes?
- georgefox 14y ago
  I'm not sure I understand why your revs would need to be perfectly matched to avoid fuel consumption. If you're slipping the clutch, you're wearing the clutch, but what does that have to do with fuel consumption? Personally, I wouldn't downshift without a rev match because of the clutch slip factor, but I was always under the impression that with the throttle closed and the engine being driven by the wheels (not by the throttle via idle), you were using virtually no fuel.
  - jamesjguthrie 14y ago
    If you don't rev match then when you down shift your revs will be higher and as such you'll be fuelling again without having to touch the throttle with your foot.

georgefox 14y ago

> I always do a combination of down-shifting and braking as this saves fuel vs purely engine braking... Assuming your car is reasonably recent, engine braking doesn't use significant fuel. See http://en.wikipedia.org/wiki/Engine_braking#Legal_implications http://en.wikipedia.org/wiki/Engine_braking#Legal_implicatio....