Knocking it into neutral

[zoros]

I had a habit of knocking my auto box into neutral everytime there was a prolonged over-run. It definitely improved my fuel consumption figures.
This is the first car however where the handbook says NOT to do this as it could damage the gearbox.

Anyone else hog neutral with their gearbox (manual or auto?

 

[KillerHERTZ]

How? You have move the shifter upwards?!?

Edit: misread your message, you do it on purpose

 

[renault12ts]

I used to do it until not to by my indie.

Something to do with oil circulation in the box, and then putting it back into drive whilst in motion.

 

[MancMike]

Why would you do this anyway?

When you come off the gas, rolling along, the gearbox shifts up to take the engine's revs down and reduce engine drag. During this there's no need to fuel the engine.

If you knock into neutral it'll then drop down to it's idle speed, where it'll have to fuel itself to keep it going.

What do you mean by "prolonged overrun"? Your box should upshift when you come off the gas to reduce engine braking. (until rpms force it to then start downshifting again to avoid stalling).

 

[zoros]

the gearbox shifts up to take the engine's revs down and reduce engine drag. During this there's no need to fuel the engine.

.

I hasten to add - that this is activity I speak about is not good practice from a motoring perspective for various reasons, but fuel economy is not one of those reasons.

As I mentioned earlier - my previous cars (including the Maserati) do not mention this in their manuals. Only the MB.

Further research suggests that knocking into neutral is only effective from a fuel saving perspective IF the car has older injectors and fuel management systems. Modern EM systems actually reverse these benefits and keeping the car in gear after taking your foot off the gas - improves fuel consumption over knocking it into neutral.

Thanks gents.

 

[KillerHERTZ]

Any savings from Fuel consumption (which I would imagine are tiny) would be offset by the wear and tear of the gearbox?

 

[Giantvanman]

Don't you have to apply the footbrake to move out of N back into D?

 

[Conquistador]

Don't you have to apply the footbrake to move out of N back into D?

Not usually when you're on the move. Only when setting off

 

[alexanderfoti]

Not usually when you're on the move. Only when setting off

Even when setting off, its only locked in P, you can move between all the other gears without your foot on the brake.

The engine will only cut off fuel above a certain rpm, and in certain scenarios putting into neutral will give you a better net fuel usage, as it will allow you to coast for longer than you could otherwise in gear.

It is still not advisable due to wear on the gearbox and also goes against the highway code.

 

[GLK]

I must confess, this and similar threads appear totally surreal to someone who learnt to drive in automatic, in an almost entirely auto environment, and have never driven (nor had any desire to) a "stick" aka manual It's been quite a few years, but I still remember what I've been told: N is for car wash only. Period! Which of course, meant any situation, when car is towed/pushed.

I can fully understand though, that coming from years of manual gearbox, it can be difficult to change habits...

 

[V8 Supercharger]

After driving only manual cars for the first 8 years after passing my test, i then bought my very first Lexus, which was my very first auto.

Never having driven an auto before i was also used to my old habit of knocking it into neutral as i came up to lights, junctions etc etc.

This worked fine for me until one day when coming upto some traffic lights i decided to do the normal trick and put it into "N" at about 30mph to just coast it to the lights. A slight lapse in concentration meant i pushed the lever just that bit too far and actually put it into "R"

Car made a few unreal noises, cut out and came to a stop. It then would not start at all. Realising i had just blown the gearbox altogether i parked it at the side of the road and walked home in a panick trying to price up a gearbox and where i would actually get one for an imported car.

About 4 hours later i went back to the car to assess the damage and try and recover it back home. This time it started, and to my amazement it even drove home. As a matter of fact it drove perfectly well for the 2 years or so i had it after that. Turns out that for some reason the Cats had overheated when i put it into reverse and for safety it would not start.

A very lucky escape for me, but iv never done that in an auto again, and have since learned about cars not using fuel when rolling in gear rather than neutral.

Could have been a very costly mistake for the few pennies i may have saved.

 

[BTB 500]

This worked fine for me until one day when coming upto some traffic lights i decided to do the normal trick and put it into "N" at about 30mph to just coast it to the lights. A slight lapse in concentration meant i pushed the lever just that bit too far and actually put it into "R"

Years ago my grandfather had a Jag XJ courtesy car while his XK150 was in the garage. He managed to ram that into reverse on the M3 by being over-enthusiastic with the shifter. Loud bang ... car kept going but had no reverse gear after that.

 

[stwat]

After driving only manual cars for the first 8 years after passing my test, i then bought my very first Lexus, which was my very first auto.

Never having driven an auto before i was also used to my old habit of knocking it into neutral as i came up to lights, junctions etc etc.

This worked fine for me until one day when coming upto some traffic lights i decided to do the normal trick and put it into "N" at about 30mph to just coast it to the lights. A slight lapse in concentration meant i pushed the lever just that bit too far and actually put it into "R"

Car made a few unreal noises, cut out and came to a stop. It then would not start at all. Realising i had just blown the gearbox altogether i parked it at the side of the road and walked home in a panick trying to price up a gearbox and where i would actually get one for an imported car.

About 4 hours later i went back to the car to assess the damage and try and recover it back home. This time it started, and to my amazement it even drove home. As a matter of fact it drove perfectly well for the 2 years or so i had it after that. Turns out that for some reason the Cats had overheated when i put it into reverse and for safety it would not start.

A very lucky escape for me, but iv never done that in an auto again, and have since learned about cars not using fuel when rolling in gear rather than neutral.

Could have been a very costly mistake for the few pennies i may have saved.

I'm very surprised it allowed you to do that. Even my 25 year old S-Class does not allow you to select reverse when the car is moving.

 

[Conquistador]

I can't think of any good reason to coast to a stop in neutral in an auto car...

On the other hand I am getting into the habit of knocking my S8 from Drive into Neutral when stationary. When I bought it the front discs were badly warped and I'm advised that after hard, long braking (A-road to a roundabout etc.) to a standstill, the pads are simply cooking the discs if left in drive which in time will indeed warp the discs.

Set of new discs is considerably cheaper than a gearbox replacement in an S8 (circa £4k) but I'm thinking this shifting from D-N-D-N-D probably isn't helping the gearbox anyway!

 

[DSM10000]

I can't think of any good reason to coast to a stop in neutral in an auto car...

On the other hand I am getting into the habit of knocking my S8 from Drive into Neutral when stationary. When I bought it the front discs were badly warped and I'm advised that after hard, long braking (A-road to a roundabout etc.) to a standstill, the pads are simply cooking the discs if left in drive which in time will indeed warp the discs.

Set of new discs is considerably cheaper than a gearbox replacement in an S8 (circa £4k) but I'm thinking this shifting from D-N-D-N-D probably isn't helping the gearbox anyway!

Or just use the parking brake and have no such problems?

 

[C180CGI]

After driving only manual cars for the first 8 years after passing my test, i then bought my very first Lexus, which was my very first auto.

Never having driven an auto before i was also used to my old habit of knocking it into neutral as i came up to lights, junctions etc etc.

This worked fine for me until one day when coming upto some traffic lights i decided to do the normal trick and put it into "N" at about 30mph to just coast it to the lights. A slight lapse in concentration meant i pushed the lever just that bit too far and actually put it into "R"

Car made a few unreal noises, cut out and came to a stop. It then would not start at all. Realising i had just blown the gearbox altogether i parked it at the side of the road and walked home in a panick trying to price up a gearbox and where i would actually get one for an imported car.

About 4 hours later i went back to the car to assess the damage and try and recover it back home. This time it started, and to my amazement it even drove home. As a matter of fact it drove perfectly well for the 2 years or so i had it after that. Turns out that for some reason the Cats had overheated when i put it into reverse and for safety it would not start.

A very lucky escape for me, but iv never done that in an auto again, and have since learned about cars not using fuel when rolling in gear rather than neutral.

Could have been a very costly mistake for the few pennies i may have saved.

Wouldent call it luck. Its a Jap Lexus :bannana:

 

[V8 Supercharger]

Wouldent call it luck. Its a Jap Lexus :bannana:

It probably was more than likely THAT factor that helped me more than my luck

But still lucky for me it was 30mph, may have been a different story at higher speed like mentioned in the Jaguar earlier by BTB 500.

 

[V8 Supercharger]

On the other hand I am getting into the habit of knocking my S8 from Drive into Neutral when stationary. When I bought it the front discs were badly warped and I'm advised that after hard, long braking (A-road to a roundabout etc.) to a standstill, the pads are simply cooking the discs if left in drive which in time will indeed warp the discs.

Set of new discs is considerably cheaper than a gearbox replacement in an S8 (circa £4k) but I'm thinking this shifting from D-N-D-N-D probably isn't helping the gearbox anyway!

I also do this in the Merc now, especially when driving on motorways or at high speeds. When i come to a stop at traffic lights, roundabouts or junctions i leave a decent gap from the car in front, then i just keep letting my car roll a little bit every couple of seconds to make sure the same bit of the disc is not overheating.

I dont think shifting it from D-N-D-N-D is doing any damage, thats what the gearbox is made for.

 

[BTB 500]

I dont think shifting it from D-N-D-N-D is doing any damage, thats what the gearbox is made for.

It's additional wear & tear on the selector mechanism, for sure.

 

[HughSurrey]

I seem to remember being told, back in the mists of time when I was learning to drive, that coasting a car is deemed as 'not being in effective control', or is that just me being befuddled?

Edit: It seems not:
Coasting is not directly illegal or against the law. Circumstances of a situation however could lead to prosecution due to coasting. If you are involved in a car accident and you were coasting at the time by having the gears in neutral, if it was found that the coasting participated somewhat to the accident, it could be deemed that the driver had a lack of control of the vehicle due to coasting.

And:

Heavy coasting such as consistently depressing the clutch whilst making turns or setting the gear stick into neutral before the car has stopped will certainly result in a failure.