coasting in neutral
12-13-2005, 01:00 PM
#41
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Originally Posted by sauceman
However, in case you choose to come back down from your ivory tower, you should know that not everyone here makes 20k/year on their car.
If I was to drive around carelessly, I would use as much as 25% more gas. If I was to buy all of my gas where I live (and not in Vt), I would pay another additionnal 25-30%.
If I was to drive around carelessly, I would use as much as 25% more gas. If I was to buy all of my gas where I live (and not in Vt), I would pay another additionnal 25-30%.
I think you're right, if you drove carelessly (or heavy-footed), you'd burn a lot more gas -- 25% is probably right. In my opinion, however, not coasting down hills doesn't make you a careless lead foot and, in itself, likely saves you next to nothing in gasoline. Driving, accelerating, and braking gently are likely what save you that 25%.
You're the gas-mileage guru, though, so maybe over 90k kms you see a real savings from coasting. Just doesn't sound like much to me vs. rolling down a hill in "D". I do wonder what the mechanical trade-off is in terms of longevity, esp. if you driving that many kms/year. And, while the likelihood is low that an unsafe condition actually emerges in front of you, the likelihood that you'll be better off in neutral than in gear is zero. Seems like a bad tradeoff to me.
12-13-2005, 01:04 PM
#42
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Originally Posted by sauceman
Probably because there could be situations where neutral could become a necessity, like if you ran out of gas.
12-13-2005, 01:09 PM
#43
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Originally Posted by peter_bigblock
Sorry, just thought the debate could use a little levity.
I think you're right, if you drove carelessly (or heavy-footed), you'd burn a lot more gas -- 25% is probably right. In my opinion, however, not coasting down hills doesn't make you a careless lead foot and, in itself, likely saves you next to nothing in gasoline. Driving, accelerating, and braking gently are likely what save you that 25%.
You're the gas-mileage guru, though, so maybe over 90k kms you see a real savings from coasting. Just doesn't sound like much to me vs. rolling down a hill in "D". I do wonder what the mechanical trade-off is in terms of longevity, esp. if you driving that many kms/year. And, while the likelihood is low that an unsafe condition actually emerges in front of you, the likelihood that you'll be better off in neutral than in gear is zero. Seems like a bad tradeoff to me.
I think you're right, if you drove carelessly (or heavy-footed), you'd burn a lot more gas -- 25% is probably right. In my opinion, however, not coasting down hills doesn't make you a careless lead foot and, in itself, likely saves you next to nothing in gasoline. Driving, accelerating, and braking gently are likely what save you that 25%.
You're the gas-mileage guru, though, so maybe over 90k kms you see a real savings from coasting. Just doesn't sound like much to me vs. rolling down a hill in "D". I do wonder what the mechanical trade-off is in terms of longevity, esp. if you driving that many kms/year. And, while the likelihood is low that an unsafe condition actually emerges in front of you, the likelihood that you'll be better off in neutral than in gear is zero. Seems like a bad tradeoff to me.
12-13-2005, 01:11 PM
#44
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Originally Posted by jlukja
If you car dies while you are moving the only way to restart it (without pulling over and stopping) is to put it into neutral and crank it. Never had to do that with my TSX but the old Dodge Dart did it once a week.
12-13-2005, 04:44 PM
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Originally Posted by peter_bigblock
I would never be driving a car coasting in neutral, MT or AT. Too many things can happen that require split-second throttle control. Really, you're going to save gasoline by rolling along in neutral? Are you going to save on your brake pads, too, by holding your hand out the window and flapping it forward before you stop?
12-13-2005, 09:39 PM
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Neutral
I was taught from when I was ye-high that a gas engine is designed to always have some load on it. I avoid neutral wherever possible. I've only used it durring an emergency when the throttle plate iced over and got stuck WOT and would not release on a previous car.
Comment from the dealer: You houldn't have done that, you might have damaged the engine/valve-stems whatever. Well I might have been killed.... The valve stems/thingamagigs can be replaced. My head/spleen/ribs can't.
I can think of a number of reasons neutral seems bad:
1) So if you're in neutral at high speeds and you forget do you slam past the redline ?
2) What about the rate of throttle change possible when the engine is in neutral. this can't be good for the engine. All momentum put in must now leave through engine internals rather than drivetrain friction.
2a) are there vibrational/mechanical harmonics with the unloaded engine ?
3) What does this do with the balance shafts internal parts that were tuned to operate under +ve load ?
4) Same as 3 but what happens in terms of mechanical stress/torque instantaneous on the drive shaft engine parts when you try to reengage from 0 or negative load to some gear ?
Comment from the dealer: You houldn't have done that, you might have damaged the engine/valve-stems whatever. Well I might have been killed.... The valve stems/thingamagigs can be replaced. My head/spleen/ribs can't.
I can think of a number of reasons neutral seems bad:
1) So if you're in neutral at high speeds and you forget do you slam past the redline ?
2) What about the rate of throttle change possible when the engine is in neutral. this can't be good for the engine. All momentum put in must now leave through engine internals rather than drivetrain friction.
2a) are there vibrational/mechanical harmonics with the unloaded engine ?
3) What does this do with the balance shafts internal parts that were tuned to operate under +ve load ?
4) Same as 3 but what happens in terms of mechanical stress/torque instantaneous on the drive shaft engine parts when you try to reengage from 0 or negative load to some gear ?
12-13-2005, 10:19 PM
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Originally Posted by crfortin
I was taught from when I was ye-high that a gas engine is designed to always have some load on it. I avoid neutral wherever possible. I've only used it durring an emergency when the throttle plate iced over and got stuck WOT and would not release on a previous car.
Comment from the dealer: You houldn't have done that, you might have damaged the engine/valve-stems whatever. Well I might have been killed.... The valve stems/thingamagigs can be replaced. My head/spleen/ribs can't.
I can think of a number of reasons neutral seems bad:
1) So if you're in neutral at high speeds and you forget do you slam past the redline ?
2) What about the rate of throttle change possible when the engine is in neutral. this can't be good for the engine. All momentum put in must now leave through engine internals rather than drivetrain friction.
2a) are there vibrational/mechanical harmonics with the unloaded engine ?
3) What does this do with the balance shafts internal parts that were tuned to operate under +ve load ?
4) Same as 3 but what happens in terms of mechanical stress/torque instantaneous on the drive shaft engine parts when you try to reengage from 0 or negative load to some gear ?
Comment from the dealer: You houldn't have done that, you might have damaged the engine/valve-stems whatever. Well I might have been killed.... The valve stems/thingamagigs can be replaced. My head/spleen/ribs can't.
I can think of a number of reasons neutral seems bad:
1) So if you're in neutral at high speeds and you forget do you slam past the redline ?
2) What about the rate of throttle change possible when the engine is in neutral. this can't be good for the engine. All momentum put in must now leave through engine internals rather than drivetrain friction.
2a) are there vibrational/mechanical harmonics with the unloaded engine ?
3) What does this do with the balance shafts internal parts that were tuned to operate under +ve load ?
4) Same as 3 but what happens in terms of mechanical stress/torque instantaneous on the drive shaft engine parts when you try to reengage from 0 or negative load to some gear ?
12-13-2005, 11:54 PM
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Lesson
If you are putting around ~80k or more milage on your car annaully, and trying to get 40 MPG efficiency, by all means, coast in neutral all you want.
However, if you are like most of the drivers who are getting about 30 MPG, I could not see any significant benefits of coasting in neutral. Seriously, if you want to do that, you might as well shut off the engine and let the car roll, but just remember to give yourself extra one and two seconds to start the car before getting back into gear when you need to regain the control of the car.
However, if you are like most of the drivers who are getting about 30 MPG, I could not see any significant benefits of coasting in neutral. Seriously, if you want to do that, you might as well shut off the engine and let the car roll, but just remember to give yourself extra one and two seconds to start the car before getting back into gear when you need to regain the control of the car.
12-14-2005, 05:13 AM
#51
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Originally Posted by BusyShifter
If you are putting around ~80k or more milage on your car annaully, and trying to get 40 MPG efficiency, by all means, coast in neutral all you want.
However, if you are like most of the drivers who are getting about 30 MPG, I could not see any significant benefits of coasting in neutral. Seriously, if you want to do that, you might as well shut off the engine and let the car roll, but just remember to give yourself extra one and two seconds to start the car before getting back into gear when you need to regain the control of the car.
However, if you are like most of the drivers who are getting about 30 MPG, I could not see any significant benefits of coasting in neutral. Seriously, if you want to do that, you might as well shut off the engine and let the car roll, but just remember to give yourself extra one and two seconds to start the car before getting back into gear when you need to regain the control of the car.
12-14-2005, 06:35 AM
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Originally Posted by jkozlow3
Not terribly likely to happen....BUT, what if you're coasting in neutral on a semi-flat surface and something fell off the back of a truck in front of you and it was rolling toward you (a steel tube, a tire, etc)?
You'd probably be much better off accelerating out of the way rather than braking and letting the rolling object fly into your car.
Just a thought.
You'd probably be much better off accelerating out of the way rather than braking and letting the rolling object fly into your car.
Just a thought.
12-14-2005, 09:30 AM
#53
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Originally Posted by BusyShifter
However, if you are like most of the drivers who are getting about 30 MPG, I could not see any significant benefits of coasting in neutral. Seriously, if you want to do that, you might as well shut off the engine and let the car roll, but just remember to give yourself extra one and two seconds to start the car before getting back into gear when you need to regain the control of the car.
If you shut off the engine you lose all the power assist (brakes, steering).
If you are coasting in neutral down a hill you are just one flick of the wrist away from being in gear (without clutching). Its no different than coasting down the hill in 6th gear in an MT. If you need to do any kind of hard acceleration to avoid a situation then 6th gear isn't going to do it for you. And, I submit that, the time it takes a person to downshift from 6th gear is the same as it would take me to shift from N to D.
12-14-2005, 09:43 AM
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Originally Posted by jlukja
I disagree.
If you shut off the engine you lose all the power assist (brakes, steering).
If you are coasting in neutral down a hill you are just one flick of the wrist away from being in gear (without clutching). Its no different than coasting down the hill in 6th gear in an MT. If you need to do any kind of hard acceleration to avoid a situation then 6th gear isn't going to do it for you. And, I submit that, the time it takes a person to downshift from 6th gear is the same as it would take me to shift from N to D.
If you shut off the engine you lose all the power assist (brakes, steering).
If you are coasting in neutral down a hill you are just one flick of the wrist away from being in gear (without clutching). Its no different than coasting down the hill in 6th gear in an MT. If you need to do any kind of hard acceleration to avoid a situation then 6th gear isn't going to do it for you. And, I submit that, the time it takes a person to downshift from 6th gear is the same as it would take me to shift from N to D.
I think most people (including myself) in this thread is saying, there are many sound and reasonable ways to increase the MPG, like don't jack rabbit start, or keep at constant speed. Sauce has more knowledge in this. Though, coasting in neutral should be the last option, if you were trying to get 40 MPG (which, I repeat, by all means, coast in neutral all you want).
12-14-2005, 08:48 PM
#55
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What you guys seem to fail to realize is that in order to use this technique well, you need to be way more concentrated on your driving than just casual cruising.
Concentrated and lots of anticipation. Therefore, the so-called security issues (though in reality nearly non-existant) are more than offset by the good driving habits required to do this well.
It's all moot. You need to do it to know what you're talking about.
Concentrated and lots of anticipation. Therefore, the so-called security issues (though in reality nearly non-existant) are more than offset by the good driving habits required to do this well.
It's all moot. You need to do it to know what you're talking about.
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