[racer_m]

Originally Posted by AjayJoshuaN

To be honest, I'm still not convinced with the reasons...

So IMO, i think that "Don't drive in neutral, always drive in gear" is just a traditional perception... I think we should make use of the momentum instead of wasting it (down hill is an exception)...

This community tries to follow and advocate tried and tested (read SAFE) driving practices.
You are free to try your own driving methodologies but we all can only advise you to be safe. Like so many others have recommended, you should certainly read up on all posts in this thread and the forum in general before suggesting your driving method should be followed by everyone.

Your driving technique is an exception and to prove your point it should have valid references and studies conducted on it, else we would have had everyone from safety experts, drivers to manufacturers telling this method.
Arguments here dont work with "I think", "I feel" type of statements

[Rehaan]

Hi AjayJoshuaN,

While the points in your last reply were certainly founded on correct logic, it's still incomplete logic - which as you might agree can lead to wrong conclusions.

I'm not going to re-type everything in this thread, but just point out some facts to consider:

1) Engines have friction.
2) This means that when an engine is idling, it is using energy (fuel) to overcome that friction and keep running.
3) This also means that when the engine is connected to the drive-train (with no accelerator input), the engine's friction is helping the car slow down.

Simply put, and additional help the brakes get is welcome.

Originally Posted by AjayJoshuaN

I think we should make use of the momentum instead of wasting it (down hill is an exception)...

Sure, if you want to just coast you'll go further without the added friction of the engine, but you will be burning fuel to idle the engine. Whereas if you were in gear, for the most part the ECU wouldn't be injecting fuel whilst you're coasting (DFCO) - leading to a possible fuel saving.

Do read the thread, or at least the starting few pages.

cya
R

[im_srini]

Originally Posted by Rehaan

...
Whereas if you were in gear, for the most part the ECU wouldn't be injecting fuel whilst you're coasting (DFCO) - leading to a possible fuel saving.
...

Hi,
It would be great if somebody could detail how the ECU determines that fuel can be "cut" safely.
Does the ECU base the fuel cut-off on just the TPS & Engine-RPM signals ?
I have an OBD device that I've used on several highway runs in both my Altos - a 13-year old Vx & a 4-year old K10.
In my Vx, the Fuel-CutOff parameter is SET ( to ON by the ECU ) when the throttle is closed & the car is coasting with the transmission in gear - this state is maintained until Engine-RPM drops to ~1,700 RPM.
In my K10 however, the Fuel-CutOff parameter is SET until Engine-RPM drops to ~1,100 RPM.
The Vx gives me ~11 Kmpl in the city & ~20 Kmpl on the highway.
The K10 gives me ~14 Kmpl in the city & ~25 Kmpl on the highway !
And, does Fuel-Cut-Off mean exactly that (?), i.e. all fuel being cut-off ?
I have a FFE & a rather LOUD end-can on the Vx - while in the Fuel-Cut-Off state, I can still hear the engine.
If fuel is cut-off, one would expect the engine note to die down isn't it ?
-

[rangakishen]

Originally Posted by im_srini

I have a FFE & a rather LOUD end-can on the Vx - while in the Fuel-Cut-Off state, I can still hear the engine.
If fuel is cut-off, one would expect the engine note to die down isn't it ?
-

I'm not sure but what you hear out of the exhaust isnt the combustion or the explosion in the combustion chamber per se. It the expansion of the hot exhaust gases rushing out the pipe. Now when fuel is cut off (either fully or to bare minimum), the engine acts like a big HOT air pump. So the air coming out of the exhaust should still be very hot and sound similar to a running engine.

And the readings on which the fueling is determined are quite a few. TPS, Engine RPM, MAF readings, Exhaust O2 sensors etc.,

Applying just basic sense would imply that fueling is determined TPS, MAF readings and Time varying RPM reading (accelerating or not).

This is just speculation. I'm no expert on this topic. Others can correct if they know for sure.

Oh and btw, my cruze MID reads 99kmpl when coasting in gear. Other cars which give fuel consumption in L/100km have been reported as showing 0l/100km when coasting in gear.

[Lobogris]

Engine braking is only useful when going downhill as it provides additional control and a bit of extra braking. For normal braking, hardly anyone slams on the brakes fully to come to a routine stop. This means that much more braking power is available than what we use when we gently coast to a planned stop. Hence there is no need to worry about an extra bit of assistance from the engine.

However it is true that coasting in neutral leads to a loss of control in case you need to accelerate. Even if one is slowing down due to a back up ahead or a light ahead, if one remains in gear, one can simply tap the accelerator if the back up clears up, the light turns green or for whatever reason. Hence it is better to leave your car in gear and simply press the clutch down once your speed decreases below the limit for that gear. After you have resolved the slowdown, you can change in appropriate gear as needed and carry on. What is not needed is to downshift from 5 to 4-3-2-1 for a planned stop. One can skip this by simply pressing the clutch.

[jinojohnt]

In the case of Automatics, I have found that braking is better if I shift from 'Drive' to 'Neutral' when the speed is less than 10 km/hr (i.e., the auto box in first gear). This might be because of the 'creeping' action of automatics in first gear, where the car is forced forward even without pressing the accelerator.

In higher gears, shifting to Neutral doesn't make the braking better (not much of a difference).

[joybhowmik]

Originally Posted by jinojohnt

In the case of Automatics, I have found that braking is better if I shift from 'Drive' to 'Neutral' when the speed is less than 10 km/hr (i.e., the auto box in first gear). This might be because of the 'creeping' action of automatics in first gear, where the car is forced forward even without pressing the accelerator.

In higher gears, shifting to Neutral doesn't make the braking better (not much of a difference).

On a planetary gear train, shifting while on the move!
You got to be brave! Or you have a lot of money!!

[jinojohnt]

Originally Posted by joybhowmik

On a planetary gear train, shifting while on the move!
You got to be brave! Or you have a lot of money!!

Or it can even be because of my ignorance .
Could you please elaborate. Forget the safety aspect, is it bad (for the auto transmission) to shift to Neutral at any speed?

Even for shifting back to 'Drive' from 'Neutral' while the car is moving, the user manual only says "do not press the accelerator while shifting, to avoid damage to the transmission".

[joybhowmik]

Originally Posted by jinojohnt

Or it can even be because of ignorance .
Could you please elaborate. Forget the safety aspect, is it bad (for the transmission) to shift to Neutral at any speed?

Going to Neutral while in motion or the reverse, quite frequently could adversely stress the clutch pack and the associated hydraulics.
Much nicer to brake to a complete halt in D mode - the way the car was designed to be used.

The only times I need to shift to N is when the car needs to be towed (last when my remote fob died, immobilizing the engine)

[anupmathur]

Originally Posted by joybhowmik

...
Much nicer to brake to a complete halt in D mode - the way the car was designed to be used.
....

Not quite true with modern cars.
Most will happily accommodate a shift from N to D while coasting at reasonable speeds.
Varies from car to car though. If there are no disturbing sounds produced in doing this N to D manoeuvre you're OK!

[joybhowmik]

Originally Posted by anupmathur

Not quite true with modern cars.
Most will happily accommodate a shift from N to D while coasting at reasonable speeds.
Varies from car to car though. If there are no disturbing sounds produced in doing this N to D manoeuvre you're OK!

Thanks
I have been driving Santro AT 2003 for last 11 years.
Before that Honda Civic 1994 AT & a Toyota Corolla 1996 AT for 4 years.
All these cars happily accommodate the shift without any complaint - guess they all fit into the modern category.
The issue is silent damage, caused due to stress on the clutch pack. It manifests itself over time - symptoms are late shifting to higher or lower gear, shifting with a jerk etc.
Once in a while if you mistakenly move N to D, is understandable, doing it as a matter of course and routine is not advisable.

[redcruiser]

how about the following situation.

I am driving at around 120 on a expressway at 5th gear. All of a sudden I see a cow appearing out of the bush and trying to cross the road on my left side (Well this is India).I have no other option but to brake hard and stop within 50meters. In this case i brake hard (not sure if the ABS will kick in) and bring the car to speed of 30kmph within 30 meters and then i downshift to 2nd gear directly skipping 4th and 3rd while still braking before coming to a halt.

Do you think this approach is correct? Will it cause any harm to any mechanical part if I skip gear while downshifting?

[Jeroen]

Originally Posted by redcruiser

Will it cause any harm to any mechanical part if I skip gear while downshifting?

No, as long as you can engage the gear without having to really force it, it is not a problem at all and there is no reason for not down shifting in one go to the appropriate gear for that reduced speed.

Jeroen

[VW2010]

i downshift to 2nd gear directly skipping 4th and 3rd while still braking before coming to a halt.

Do you think this approach is correct? Will it cause any harm to any mechanical part if I skip gear while downshifting?

Its perfectly fine. Gear shift just needs right engine speed to have the best possible gear shift. So when you are slowing down your Engine RPM also slows down and unless you are at red in your RPM gauge a downshift only removes the load from the gears there by allowing engine to gain some RPM.

An old cast iron bullet with a neutral shift lever is the best thing to learn about this. The gear patter in those bikes(i own one) is 1-2-3-4, 4 to neutral and either 1st or 2nd from there. Wonderful little feature.

And if you want to be in the turbo band and power band in a car, people usually downshift to keep the RPM high enough to always be in that power band in all gears. And some do the heal/toe shifting to give enough RPM for the engine to not lose any power during those downshifts.

The gears are not sequential in either direction. As much as you can downshift from 5 to 1, you can also upshift from 1 to 5 except that you may stall the engine based on the engine RPM

[vsathyap]

Originally Posted by redcruiser

how about the following situation.

I am driving at around 120 on a expressway at 5th gear. All of a sudden I see a cow appearing out of the bush and trying to cross the road on my left side (Well this is India).I have no other option but to brake hard and stop within 50meters.

Funnily enough (or actually - it was not all that funny when it happened ), something very similar happened during one of my drives a couple of weeks ago. I was on a 2 lane state highway with light-moderate traffic (with the usual lunas and bikes and diesel 3 wheelers that make the dug-dug sound) and I was doing 40-50kmph when a one cow from a herd of cows walking on the opposite lane sidewalk decided to "panic-cross" the road in front of my car and it ran straight towards my car. This happened fairly close to me (I doubt if it was even 30-40 feet away) and I immediately stood on the brake pedal!

In this sudden situation, I totally did not have the time to either downshift or even press the clutch. The wonderful brakes with ABS helped me steer towards the left of the road while I was braking and come to a dead stop just millimeters from the cow! The cow looked like it didnt care on what had happened and simply walked away Obviously, as I didn't even have the time to press the clutch, the engine stalled. I just started the car, reversed a bit so that I am aligned with the road and went on my way - no drama whatsoever.

Question here is - in such millisecond-microsecond situations, I did not even have the time to press the clutch pedal - how can one assume they can downshift safely and let engine braking come into effect?

Agreed, if the obstacle on the road is a few hundred meters away, it may be an option but sudden braking like the one I experienced, I could barely lift my left foot off the ground and by then, the car had stalled. So, is this discussion even practical?