Coasting in Neutral
Discussion
CoreyDog said:
Really.
So on a gradual why not hold the car in 4th, 5th or even 6th?
If the car is in neutral, you are sacrificing some control over that car, what if you need to accelerate quickly to avoid an emerging hazard? All well and good sat there with a revving engine and making no more progress.
Because in 4/5/6 you will not ‘coast’ very far at all due to engine braking, as said, only on a steeper slope is this strategy better.So on a gradual why not hold the car in 4th, 5th or even 6th?
If the car is in neutral, you are sacrificing some control over that car, what if you need to accelerate quickly to avoid an emerging hazard? All well and good sat there with a revving engine and making no more progress.
E.g. see here:
https://youtu.be/_bZlb62VVlw
CoreyDog said:
Really.
So on a gradual why not hold the car in 4th, 5th or even 6th?
If the car is in neutral, you are sacrificing some control over that car, what if you need to accelerate quickly to avoid an emerging hazard? All well and good sat there with a revving engine and making no more progress.
Have ou ever driven a car with a modern DSG box ? Power is back on pretty much instantaneously if you need it.So on a gradual why not hold the car in 4th, 5th or even 6th?
If the car is in neutral, you are sacrificing some control over that car, what if you need to accelerate quickly to avoid an emerging hazard? All well and good sat there with a revving engine and making no more progress.
Narcisus said:
CoreyDog said:
Really.
So on a gradual why not hold the car in 4th, 5th or even 6th?
If the car is in neutral, you are sacrificing some control over that car, what if you need to accelerate quickly to avoid an emerging hazard? All well and good sat there with a revving engine and making no more progress.
Have ou ever driven a car with a modern DSG box ? Power is back on pretty much instantaneously if you need it.So on a gradual why not hold the car in 4th, 5th or even 6th?
If the car is in neutral, you are sacrificing some control over that car, what if you need to accelerate quickly to avoid an emerging hazard? All well and good sat there with a revving engine and making no more progress.
Advanced driving must have changed massively since I passed my IAM in 2009 and my ROSPA 3 years ago. Coasting was a massive no no due to the lose of control it causes.
CoreyDog said:
I haven't. My car has a dual clutch box but it's a Getrag. It only disengages the clutch when on the brakes. On steep inclines I'll switch into manual and depending on the gradient it will be 3rd or 4th usually.
Advanced driving must have changed massively since I passed my IAM in 2009 and my ROSPA 3 years ago. Coasting was a massive no no due to the lose of control it causes.
Agreed with a manual but would VAG include it if they thought it was risky ? Anyway I dont use it.Advanced driving must have changed massively since I passed my IAM in 2009 and my ROSPA 3 years ago. Coasting was a massive no no due to the lose of control it causes.
CoreyDog said:
I haven't. My car has a dual clutch box but it's a Getrag. It only disengages the clutch when on the brakes. On steep inclines I'll switch into manual and depending on the gradient it will be 3rd or 4th usually.
Advanced driving must have changed massively since I passed my IAM in 2009 and my ROSPA 3 years ago. Coasting was a massive no no due to the lose of control it causes.
I think when I learnt to drive (20 odd years ago) I was told not to overuse coasting as you weren't in proper control of the vehicle. Cars have changed quite bit since then though I guess.Advanced driving must have changed massively since I passed my IAM in 2009 and my ROSPA 3 years ago. Coasting was a massive no no due to the lose of control it causes.
My Mazda 6 actively encourages coasting in gear but that might be to recharge the i-eloop system thing which saves fuel in other ways. I've always coasted in the highest gear possible to maximise the distance covered while coasting, only coming down a gear or 2 when the speed is so low the car is about to start struggling.
Narcisus said:
Agreed with a manual but would VAG include it if they thought it was risky ? Anyway I dont use it.
Many manufacturers include fuel savings systems that are not idea and in some cases just dangerous. Ford, Merc, Volvo and VAG cars will all kill the engine whilst it is still actually moving. MuscleSedan said:
As you would expect, DSG Eco mode causes upshifts to be as soon as they possibly can, along with providing the coasting feature. There's no reduction in actual engine power output. Its a bit weird at first as you come off the throttle the revs drop to idle and you lose the braking effect between the engine and transmission. Its surprising how far you can go on a long gentle descent with the engine at idle though. A definite fuel saver but there's no way I could drive around using it all the time.
Are you sure it doesn't reduce the power output? My wife drove her DSG A3 (petrol, if that makes a difference) in Eco mode around town for a while as she couldn't really tell the difference, but trying to accelerate onto a dual carriageway it didn't really want to accelerate so she's put it back in normal and hasn't tried it since!I tried it once or twice and had to keep on the brake going downhill in a 30 as it was in neutral and kept accelerating over the limit.
Try neutral if you want to, on the westbound downhill M40 near Stokenchurch.
Car will maintain a steady speed for quite a distance, but then your speed will increase.
The total free wheeling distance can be more than 1 mile.
As speed begins to reduce, increase engine speed to about 2,000 rpm, then select D or 5th gear for a smooth take up of power.
On a long journey, probably makes hardly any difference to overall fuel consumption.
Don't try that when other traffic is near to you.
Depends on the decline but according to my experience coasting in neutral is better than leaving it in gear with no throttle.
Even on the slightest of declines, throttling up to 30mph and popping it into neutral, the car will just keep rolling for half a mile. Same stretch of road in gear the car will just stall after 100 yards.
Even on the slightest of declines, throttling up to 30mph and popping it into neutral, the car will just keep rolling for half a mile. Same stretch of road in gear the car will just stall after 100 yards.
Starfighter said:
Narcisus said:
Agreed with a manual but would VAG include it if they thought it was risky ? Anyway I dont use it.
Many manufacturers include fuel savings systems that are not idea and in some cases just dangerous. Ford, Merc, Volvo and VAG cars will all kill the engine whilst it is still actually moving. Me I'll use gears thanks, remember coming down several miles of mountain pass in Spain, overloaded econobox skoda PoS, sheer drop to one side and some very Spanish driving going on to the other, every time I dropped cogs for a hairpin I'd have the FiL complaining in my ear can I ride the brakes more cos we're low on fuel and he doesn't want to have to put more in before returning it... No thanks mate I know overheated brakes isn't generally a thing but I'd rather keep mine tip top and risk paying for another litre or whatever of petrol ffs.
I was not referring to the zero fuel overrun condition, I understand this and agree it is logical.
My concern has been a number of vehicles that will kill the engine completely via the auto start /stop whilst the wheels are still turning.
Back to the OP - considering this is an Advanced Driving thread you may wish to consider that your priority is safety then coasting in neutral will give less control than in gear. Down hill the car can start to runaway without the benefit of engine braking.
My concern has been a number of vehicles that will kill the engine completely via the auto start /stop whilst the wheels are still turning.
Back to the OP - considering this is an Advanced Driving thread you may wish to consider that your priority is safety then coasting in neutral will give less control than in gear. Down hill the car can start to runaway without the benefit of engine braking.
Some of the newer systems actually switch the engine off, which is pretty clever.
Obviously it saves fuel or the manufacturer wouldn't have bothered doing it.
It's basically just down to being able to "coast" for longer than if you were in gear.
E.g. say you have 1km to a roundabout, you can either:
Continue for half a km at 60mph in gear, then lift off at 0.5 km and overrun down to 30mph at the 1 km mark. So for half a km you've used no fuel, but for the other half you've used whatever it takes to drive at 60 mph.
Or you could put it in neutral at the start, and coast more gradually down to 30mph by the end. This way you've been using fuel for the full distance, but only at the idle consumption rate.
Numbers above are completely made up but you get the idea.
If you lift off at the same point you would have done "in gear" then you won't save any fuel, and you'll use more braking. If you lift off earlier and use neutral you might save some. Obviously there is a crossover point somewhere.
Obviously it saves fuel or the manufacturer wouldn't have bothered doing it.
It's basically just down to being able to "coast" for longer than if you were in gear.
E.g. say you have 1km to a roundabout, you can either:
Continue for half a km at 60mph in gear, then lift off at 0.5 km and overrun down to 30mph at the 1 km mark. So for half a km you've used no fuel, but for the other half you've used whatever it takes to drive at 60 mph.
Or you could put it in neutral at the start, and coast more gradually down to 30mph by the end. This way you've been using fuel for the full distance, but only at the idle consumption rate.
Numbers above are completely made up but you get the idea.
If you lift off at the same point you would have done "in gear" then you won't save any fuel, and you'll use more braking. If you lift off earlier and use neutral you might save some. Obviously there is a crossover point somewhere.
Starfighter said:
I was not referring to the zero fuel overrun condition, I understand this and agree it is logical.
My concern has been a number of vehicles that will kill the engine completely via the auto start /stop whilst the wheels are still turning.
Back to the OP - considering this is an Advanced Driving thread you may wish to consider that your priority is safety then coasting in neutral will give less control than in gear. Down hill the car can start to runaway without the benefit of engine braking.
if at speed that's plain stupid. What if for whatever reason it can't restart? I guess the brake servos electric at least? Not too likely I know, I lost the engine in a van in the outside lane of a motorway once, straightaway was moving slower than lane 2 who were then most reluctant to let me me over - had to near force my way through so as not to have to stop in L3.My concern has been a number of vehicles that will kill the engine completely via the auto start /stop whilst the wheels are still turning.
Back to the OP - considering this is an Advanced Driving thread you may wish to consider that your priority is safety then coasting in neutral will give less control than in gear. Down hill the car can start to runaway without the benefit of engine braking.
Mind, stopstart is the work of Satan himself.
Teddy Lop said:
if at speed that's plain stupid. What if for whatever reason it can't restart? I guess the brake servos electric at least? Not too likely I know, I lost the engine in a van in the outside lane of a motorway once, straightaway was moving slower than lane 2 who were then most reluctant to let me me over - had to near force my way through so as not to have to stop in L3.
Mind, stopstart is the work of Satan himself.
Some cars just use the ABS modulator as a servo now, so there is no vacuum requirement anymore. Although I'm pretty sure some the cars that switch the engine fully off do have conventional boosters. Yes the engine may not restart but you'd have to pump the pedal a lot of times to lose all your assistance, by which time you'd be stopped anyway.Mind, stopstart is the work of Satan himself.
The engine could also seize while in gear, which wouldn't be nice either.
Three points to make here:
In direct answer to the OP, my current daily driver, a 2016 530d, has a coasting feature you can turn off and on via the iDrive, and in my 75 miles a day commute on a mix of roads (20 minutes C roads, 25 minutes dual carriageway, 10 minutes urban 30mph limit, 45 minutes winding A/B roads) it's worth 2mpg, or 4.5% on my winter economy (45mpg to 47mpg). That's after multiple tests with a high degree of repeatability. The car runs an 8 speed automatic gearbox and both tests were done in "eco pro" mode, which softens throttle response and changes gear for economy.
To reply to the comment about closing the throttle using less fuel than coasting in neutral, yes, this is true per unit time (e.g. 10 seconds), but because engine braking slows the car more quickly, coasting is better per unit distance - i.e. you can typically coast for much longer, either maintaining speed on a slight downhill, or going from one speed to another (for example, entering a lower speed limit). For my daily driver (3 litres and 6 cylinders), engine braking is a very noticeable effect and there's a huge difference between backing off and coasting. For example, every day I approach a 30 limit from a 50mph limit - with coasting enabled I back off about 1km before the 30, but without it enabled, just backing off the throttle in gear, it's more like 300-400 metres.
On a closing note, with regard to advanced driving, coasting is not particularly safe because you don't have full control of your car. This counts both for fine control of balance and therefore grip in a corner, but also the ability to accelerate if a situation requires it.
In direct answer to the OP, my current daily driver, a 2016 530d, has a coasting feature you can turn off and on via the iDrive, and in my 75 miles a day commute on a mix of roads (20 minutes C roads, 25 minutes dual carriageway, 10 minutes urban 30mph limit, 45 minutes winding A/B roads) it's worth 2mpg, or 4.5% on my winter economy (45mpg to 47mpg). That's after multiple tests with a high degree of repeatability. The car runs an 8 speed automatic gearbox and both tests were done in "eco pro" mode, which softens throttle response and changes gear for economy.
To reply to the comment about closing the throttle using less fuel than coasting in neutral, yes, this is true per unit time (e.g. 10 seconds), but because engine braking slows the car more quickly, coasting is better per unit distance - i.e. you can typically coast for much longer, either maintaining speed on a slight downhill, or going from one speed to another (for example, entering a lower speed limit). For my daily driver (3 litres and 6 cylinders), engine braking is a very noticeable effect and there's a huge difference between backing off and coasting. For example, every day I approach a 30 limit from a 50mph limit - with coasting enabled I back off about 1km before the 30, but without it enabled, just backing off the throttle in gear, it's more like 300-400 metres.
On a closing note, with regard to advanced driving, coasting is not particularly safe because you don't have full control of your car. This counts both for fine control of balance and therefore grip in a corner, but also the ability to accelerate if a situation requires it.
Edited by RobM77 on Wednesday 15th January 13:46
when I learned to drive 32 years ago, I am sure I was told it was illegal to coast? A quick google search...
The Highway code states:
This term describes a vehicle travelling in neutral or with the clutch pressed down. Do not coast, whatever the driving conditions. It reduces driver control because:
Engine braking is eliminated.
Vehicle speed downhill will increase quickly.
Increased use of the footbrake can reduce its effectiveness.
Steering response will be affected particularly on bends and corners.
It may be more difficult to select the appropriate gear when needed.
The Highway code states:
This term describes a vehicle travelling in neutral or with the clutch pressed down. Do not coast, whatever the driving conditions. It reduces driver control because:
Engine braking is eliminated.
Vehicle speed downhill will increase quickly.
Increased use of the footbrake can reduce its effectiveness.
Steering response will be affected particularly on bends and corners.
It may be more difficult to select the appropriate gear when needed.
RobM77 said:
Three points to make here:
For my daily driver (3 litres and 6 cylinders), engine braking is a very noticeable effect and there's a huge difference between backing off and coasting. For example, every day I approach a 30 limit from a 50mph limit - with coasting enabled I back off about 1km before the 30, but without it enabled, just backing off the throttle in gear, it's more like 300-400 metres.
I don't think I could be that patient - and if you don't take advantage of the system by backing off earlier the economy could be worse rather than better. In my wife's car the feature is enabled in Eco mode - which we don't use. For my daily driver (3 litres and 6 cylinders), engine braking is a very noticeable effect and there's a huge difference between backing off and coasting. For example, every day I approach a 30 limit from a 50mph limit - with coasting enabled I back off about 1km before the 30, but without it enabled, just backing off the throttle in gear, it's more like 300-400 metres.
Edited by RobM77 on Wednesday 15th January 13:46
Gassing Station | Advanced Driving | Top of Page | What's New | My Stuff