Driver Profile Selection - Coasting Function

[Baz 55]

I'm not sure if all Mk 7 with DSGs have a coasting mode or mine has because it has a DA pack BUT -
I am becoming quite an expert in coasting and am freaked out just how far the Dub will coast for.
Around the area I live I have learnt to take my foot off the accelerator sooner and sooner now realising the potential of coast mode.
I have traveled 3000k and mostly urban and outer urban driving and am currently averaging 5.2l per 100km in economy mode. I reckon this is really good and put a lot of it down to the ability to coast a lot.
Is anyone else using Coast mode ?
How is it going ?

[DP Vic]

the coasting is amazing... so is the auto hold brake... i'm going to be such a lazy driver hahaha

[caeci11ius]

Loving the coast. Have been getting great fuel consumption between that and the cruise control around Canberra (conditions well suited to use of both). Not sure the standard models (without driver assist) have it...certainly the shifter is only labelled D/S (not D/S/E; the three modes on mine).

Turned off the auto hold brake incidentally...perfer the start/stop to activate the engine when I take my foot off the brake (gives it a little more time to react before I take off). The start/stop was the one thing that annoyed me in the test drive, so I was glad to discover it was able to work this way...

[Mountainman]

Mine is a manual and assume it doesn't have coast mode but I've really had to adjust my driving technique to account for the way the car just keeps rolling and rolling along after lifting off the accelerator. It feels like there is no wind or road resistance at all. It's such a contrast to the Forester I also drive which feels like the brakes have been applied when coasting.

[tonymy01]

Yep, even my mk6 AWD, also a manual, coasts a hell of a lot better than my old MY01 WRX. I guess it just has a lot less rolling resistance, even coasting in a low gear like 4th (thinking down Warringah Rd over the Roseville bridge where you can be breaking the speed limit in 4th with zero throttle. Looking at the instantaneous fuel used in the MFD, it is nice to see zero for so long while maintaining a high speed :)

[Idle]

So what's new? I had a 1950's Rover with selectable freewheel — which also made clutchless changes a doddle.

Plus in the 1940's lived at the top of a long hill.

My 1923 Dodge would roll about a mile and a half with the motor turned off and went faster — and ever so much smoother — than it could under power (alas, rolling in "angel gear" is now banned...)

[Baz 55]

Idle - by name and by nature - a conservationist well before your time. lol
My first car was a VW Beetle 1962 an absolute piece of crap and it rolled heaps !!!! However I had to push it - a lot :-)

[GeckoZAO]

yeah loving coasting, but isnt it similar to N gear for manuals when rolling (just guessing, be nice!!! XD)
i live in the cbd, 500kms done so far, 8.4L/100km average speed 24km. so sad...

[Eaglehawk]

I use to drive my Mk 5 2.0 TDI DSG like it had coast mode (manually selecting N). But from what I've read in the manual, and road rules, it's now illegal to do so. (And apparently bad for the clutch?)

[tonymy01]

yeah loving coasting, but isnt it similar to N gear for manuals when rolling (just guessing, be nice!!! XD)

The N gear uses fuel though (as in, for the engine to run, it runs at idle in N, you can see the MFD shows litres/HR on the instantaneous view), the coasting I was referring to was in gear,foot off throttle, the engine shuts off fuel entirely (as the engine is being kept rotated by the drivetrain).

[Mountainman]

The N gear uses fuel though (as in, for the engine to run, it runs at idle in N, you can see the MFD shows litres/HR on the instantaneous view), the coasting I was referring to was in gear,foot off throttle, the engine shuts off fuel entirely (as the engine is being kept rotated by the drivetrain).
That's how my manual works. In neutral it uses .5L/hour with aircon off and .7L/hour with aircon on. When lifting off in gear it shows 0L/100km and feels like it's going to roll on forever.

btw The other day my touchscreen showed 227km travelled in 2.53h at 79km/h with 980km range and average 4.5L/100km. Just typical country driving with other traffic at speed limits. I reckon that's pretty good for a petrol engine. It makes me wonder if it could ever do 1200km on a tank full like the readout predicts.

[tonymy01]

The only way I can imagine this works given the engine has quite high compression is that it somehow opens the exhaust valves early to reduce the compression during the compression stroke.

[kure69]

The way I get the car to roll further is foot off the accelerator and push the gear stick into s mode. It will hold the gear box into higher gear and will not down shift so soon.

[GeckoZAO]

That's how my manual works. In neutral it uses .5L/hour with aircon off and .7L/hour with aircon on. When lifting off in gear it shows 0L/100km and feels like it's going to roll on forever.

btw The other day my touchscreen showed 227km travelled in 2.53h at 79km/h with 980km range and average 4.5L/100km. Just typical country driving with other traffic at speed limits. I reckon that's pretty good for a petrol engine. It makes me wonder if it could ever do 1200km on a tank full like the readout predicts.

wow, impressive!
i hope mine gets low soon after run-in, 500km so far, 28km avg and 8.4L/100km.
keep it up!

[GeckoZAO]

noticed sometimes when im coasting downhill at 70-80km/h, there is no 'eco' icon on MFD, and engine rev is about 3k, consumption was showing 0L/100km. so why it keeps rev up instead of like coasting when rev is under 1k?

[wai]

Actually DSGs have had coast available for quite a while. Depending on the attitude of the car, it will also hold a gear to help you on a descent.

Coasting in a standard manual is not something looked on too favourably. If you "dead stick" (i.e. put the transmission in neutral without the vehicle being at a standstill), it would be an instant fail in a driving test, and would not be looked on favourably by an insurer either.

Trying to re-engage the transmission after coasting can also place you at risk. There is a huge difference between an automated manual doing this and the driver doing this.

[brimway]

My Father had a Rover 90 and he used to change gear, once mobile, without disengaging the clutch. Was that the big round knob near the gear stick?


So what's new? I had a 1950's Rover with selectable freewheel — which also made clutchless changes a doddle.

Plus in the 1940's lived at the top of a long hill.

My 1923 Dodge would roll about a mile and a half with the motor turned off and went faster — and ever so much smoother — than it could under power (alas, rolling in "angel gear" is now banned...)

[Idle]

My Father had a Rover 90 and he used to change gear, once mobile, without disengaging the clutch. Was that the big round knob near the gear stick?

Yes — it was a Rover feature for many years.

[46neil]

currently the coasting function is only active in ECO MODE, I want to enable coasting function, with the engine in Normal Mode, does anyone know that can be done.
cheers Neil

[stedes]

Actually DSGs have had coast available for quite a while. Depending on the attitude of the car, it will also hold a gear to help you on a descent.

Coasting in a standard manual is not something looked on too favourably. If you "dead stick" (i.e. put the transmission in neutral without the vehicle being at a standstill), it would be an instant fail in a driving test, and would not be looked on favourably by an insurer either.

Trying to re-engage the transmission after coasting can also place you at risk. There is a huge difference between an automated manual doing this and the driver doing this.


Yes, DSG and other more recent automatic gearboxes (e.g. ZF) have had this feature for a while. Rather than the gearbox changing up to the highest gear possible (i.e. to keep the revs as low as possible like old slushmatics do) when you take your foot off the accelerator, these boxes change down so the car "coasts" as if the engine is not there, keeping the revs higher. The ECU shuts off the fuel to the engine so the only thing turning the engine is effectively the momentum of the car (from the drivetrain). Similar thing to "engine braking" which manual drivers were taught to do on downhill bits so that your car was more stable and your brakes didn't get a beating (albeit done for reasons other than economy).

You can do it with a manual and it definitely does not involve putting it in neutral which, as you said, is very bad practice and if someone's doing that to save fuel it just shows that they don't know how their car works. As someone mentioned before, neutral will return the engine to idle speed and as there is nothing else keeping the engine turning it will start using fuel again. The fuel cut off in this manner is something that has been done for many years and if you look at old car brochures (e.g. E34 BMW of the late 80s) the feature was sometimes called "fuel cut off on the overrun".

I am really looking forward to trying all this and seeing what difference it make in economy...still 2.5 months to go!

[zardoz]

During my test drive of a 103TSI wagon the other day, I observed that the car would roll a lot further/more easily than my current 118TSI wagon so they have definitely improved some stuff here. I usually average around 6.5-6.8L/100km in the Mark 6 wagon (that's with a clutch pack that still shudders/slips) so I'm realistically expecting around 5.3-5.4 with the new one given the way I drive. I hope!!

[GeckoZAO]

During my test drive of a 103TSI wagon the other day, I observed that the car would roll a lot further/more easily than my current 118TSI wagon so they have definitely improved some stuff here. I usually average around 6.5-6.8L/100km in the Mark 6 wagon (that's with a clutch pack that still shudders/slips) so I'm realistically expecting around 5.3-5.4 with the new one given the way I drive. I hope!!

80% city 20% highway for me, 7L/100km.
my record is 5.1L/100km from blackburn rd to city via M3. ;)

[jaysingh]

Hi All,

Apologies if this has already been answered somewhere.

Does MY16 Golf have the coasting feature?

Thanks

[110Rliner]

You've got to have the Driver Assistance Package so you get the vehicle profile selection.

From there, if you put the car into ECO mode you will get proper coasting.

[jaysingh]

ooh :(

[agentthumb]

ooh :(

You are not missing out on much anyway unless you live in the middle of nowhere with straight roads, no traffic and loads of traffic lights.

The system decouples clutch when you back off throttle, essentially putting the car in neutral, only engaging the clutch again when you:
1. Go back on throttle (with major delays due to gear selection etc) or
2. Brake (and it doesn't disengage again even if you only touch the brakes unless you touch the go peddle again)

The system is great in principal, however let's look at real world usage:

Generally, in city traffic, you back off throttle because the car in front has started to slow down, you are going downhill or you are rolling to a set of lights. In this state, the car is not burning any fuel, and this usually provides enough resistance for you to hold speed (downhill), or roll to a stop with reasonable pace.

However, with ECO mode, the following situations occur:

1. Going downhill - Clutching out is useless as you pick up speed like a run away car, so you have to use the brake anyway to shave off the extra speed you have just picked up. Clutch engages.
2. Car infant of you slowing down - Clutching out means you roll a bit further, but it also mean you will catch up to the car in front really quickly, so you need to apply brake. Clutch engages.
3. Rolling to a set of lights - Again, unless you live in the condition first described, or it's the middle of the night in city areas, there are hardly any chances where you could back off throttle 3-500m before a set of lights and just roll to a stop without pissing the **** out of the guy behind you.

4. And this is a big one - When you de-clutch, you are still burning fuel to keep the engine idle. So while in normal mode, you burn 0 fuel rolling to a stop, in ECO, you actually burn fuel while your car is coasting. This is fine if you have the luxury of rolling for a long time so your fuel usage is offset by your rolling distance. However, in city conditions, you generally roll for a small distance, only to have to brake (usually harder to compensate for your faster rolling speed in ECO) to stop, in this case, you are not really saving any fuel.

While I don't have conclusive evidence to back up my claims, my limited testing has shown ECO mode to use more fuel during peak hour traffic compared to just using Normal. Both done with AC off, windows up, but are subject to the traffic conditions at the time. Having said that, fuel figures for both modes came back at about 6 l/100k or 6.2 l/100k, so the difference is not great by any means.

[turtle]

You are not missing out on much anyway unless you live in the middle of nowhere with straight roads, no traffic and loads of traffic lights.

The system decouples clutch when you back off throttle, essentially putting the car in neutral, only engaging the clutch again when you:
1. Go back on throttle (with major delays due to gear selection etc) or
2. Brake (and it doesn't disengage again even if you only touch the brakes unless you touch the go peddle again)

The system is great in principal, however let's look at real world usage:

Generally, in city traffic, you back off throttle because the car in front has started to slow down, you are going downhill or you are rolling to a set of lights. In this state, the car is not burning any fuel, and this usually provides enough resistance for you to hold speed (downhill), or roll to a stop with reasonable pace.

However, with ECO mode, the following situations occur:

1. Going downhill - Clutching out is useless as you pick up speed like a run away car, so you have to use the brake anyway to shave off the extra speed you have just picked up. Clutch engages.
2. Car infant of you slowing down - Clutching out means you roll a bit further, but it also mean you will catch up to the car in front really quickly, so you need to apply brake. Clutch engages.
3. Rolling to a set of lights - Again, unless you live in the condition first described, or it's the middle of the night in city areas, there are hardly any chances where you could back off throttle 3-500m before a set of lights and just roll to a stop without pissing the **** out of the guy behind you.

4. And this is a big one - When you de-clutch, you are still burning fuel to keep the engine idle. So while in normal mode, you burn 0 fuel rolling to a stop, in ECO, you actually burn fuel while your car is coasting. This is fine if you have the luxury of rolling for a long time so your fuel usage is offset by your rolling distance. However, in city conditions, you generally roll for a small distance, only to have to brake (usually harder to compensate for your faster rolling speed in ECO) to stop, in this case, you are not really saving any fuel.

While I don't have conclusive evidence to back up my claims, my limited testing has shown ECO mode to use more fuel during peak hour traffic compared to just using Normal. Both done with AC off, windows up, but are subject to the traffic conditions at the time. Having said that, fuel figures for both modes came back at about 6 l/100k or 6.2 l/100k, so the difference is not great by any means.
I was thinking the exact same thing when I played around with Eco mode in my GTI. When it's 'coasting' its actually using fuel to keep the engine running at idle (although it displays 'eco' instead of a l/100km or l/hr number). Seems kinda pointless to me.

[agentthumb]

Exactly!

Where it would save you fuel is the lower up shift point and altered aircon profile :) the car gets real warm tho before it would kick back in at the lights...


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[Carsten]

The coasting function facilitates conservation of momentum - unlike normal torque-converter automatics which engine brake every time you lift the throttle. When you DO want engine braking with a VW DSG, you just tap the brakes. So coasting function gives you the option - engine braking or not - where is the downside? I appreciate it very much.


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[pologti18t]

The coasting function facilitates conservation of momentum - unlike normal torque-converter automatics which engine brake every time you lift the throttle. When you DO want engine braking with a VW DSG, you just tap the brakes. So coasting function gives you the option - engine braking or not - where is the downside? I appreciate it very much.
k

ZF disagrees with you

ZF begins production of second-generation eight-speed automatic transmission (http://www.caradvice.com.au/303399/zf-begins-production-of-second-generation-eight-speed-automatic-transmission/)


The transmission’s ‘coasting’ function – the uncoupling of the gearbox and simultaneous stopping of the engine – now operates at speeds up to 160km/h. ZF has also further optimised the stop/start function, with the engine now stopping immediately as the vehicle stops, rather than waiting 1.5 seconds as in the original eight-speed.

[danielb_c]

4. And this is a big one - When you de-clutch, you are still burning fuel to keep the engine idle. So while in normal mode, you burn 0 fuel rolling to a stop, in ECO, you actually burn fuel while your car is coasting. This is fine if you have the luxury of rolling for a long time so your fuel usage is offset by your rolling distance. However, in city conditions, you generally roll for a small distance, only to have to brake (usually harder to compensate for your faster rolling speed in ECO) to stop, in this case, you are not really saving any fuel.



What makes you think coasting with clutches disengaged would use any more fuel than rolling to a stop in gear? The engine is still turning over, spark plugs firing, energy is still needed to run your other systems. With all due respect, just because your dash is telling you you're using NIL fuel, doesn't mean it's true.

If anything you should be using less fuel while coasting because the RPM is lower than when in gear, and there's no load.

Giving yourself more distance to the car in front improves efficiency (Eco mode or otherwise) because you're not having to brake as often, therefore you're also not having to accelerate as often. Hence why cars with ACC have a larger gap to the car in front in Eco mode than in other modes.

[agentthumb]

What makes you think coasting with clutches disengaged would use any more fuel than rolling to a stop in gear? The engine is still turning over, spark plugs firing, energy is still needed to run your other systems. With all due respect, just because your dash is telling you you're using NIL fuel, doesn't mean it's true.

If anything you should be using less fuel while coasting because the RPM is lower than when in gear, and there's no load.

Giving yourself more distance to the car in front improves efficiency (Eco mode or otherwise) because you're not having to brake as often, therefore you're also not having to accelerate as often. Hence why cars with ACC have a larger gap to the car in front in Eco mode than in other modes.

Refer to discussion here. Please explain how my car uses NO fuel while in gear coasting downhill?? - TDIClub Forums (http://forums.tdiclub.com/showthread.php?t=226400)

Also, I have ACC. Eco makes no difference to ACC distance. The two are independent. It may appear so because ACC is slow as hell when in Eco, which I set in individual mode. This takes advantage of the slow response, but coasting feature doesn't activate when set in individual mode. Perfect when using ACC to crawl in traffic.


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[danielb_c]

Refer to discussion here. Please explain how my car uses NO fuel while in gear coasting downhill?? - TDIClub Forums (http://forums.tdiclub.com/showthread.php?t=226400)

Also, I have ACC. Eco makes no difference to ACC distance. The two are independent. It may appear so because ACC is slow as hell when in Eco, which I set in individual mode. This takes advantage of the slow response, but coasting feature doesn't activate when set in individual mode. Perfect when using ACC to crawl in traffic.


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The link in the thread appears broken, but after my own Google search I do stand corrected good sir! Thanks for pointing me in the right direction.

FYI: Coasting in Neutral or Gear to Save Gas - Coasting and Fuel Economy (http://www.popularmechanics.com/cars/hybrid-electric/a5977/coasting-in-neutral-fuel-economy/)

The challenge I would have to this, however, is it assumes there is zero throttle input in both scenarios. Where the hill is not a significant grade, being in gear may actually require you to use some throttle to maintain a constant speed due to the drag the drivetrain creates, and therefore you would use some fuel, whereas coasting would likely be longer before a throttle input is required. Which one is more, I don't know, but I'm sure someone out there has tested it.

I, personally, get the best fuel economy when there's no traffic, because I'm not having to adjust speed because of the person in front's inability to maintain a constant speed, and also I can allow the car's speed to fluctuate a little with the undulations (letting off the accelerator early over the crest of a hill, or allowing it to go a little over the speed limit down a hill when there's an uphill coming, etc)

[agentthumb]

The link in the thread appears broken, but after my own Google search I do stand corrected good sir! Thanks for pointing me in the right direction.

FYI: Coasting in Neutral or Gear to Save Gas - Coasting and Fuel Economy (http://www.popularmechanics.com/cars/hybrid-electric/a5977/coasting-in-neutral-fuel-economy/)

The challenge I would have to this, however, is it assumes there is zero throttle input in both scenarios. Where the hill is not a significant grade, being in gear may actually require you to use some throttle to maintain a constant speed due to the drag the drivetrain creates, and therefore you would use some fuel, whereas coasting would likely be longer before a throttle input is required. Which one is more, I don't know, but I'm sure someone out there has tested it.

I, personally, get the best fuel economy when there's no traffic, because I'm not having to adjust speed because of the person in front's inability to maintain a constant speed, and also I can allow the car's speed to fluctuate a little with the undulations (letting off the accelerator early over the crest of a hill, or allowing it to go a little over the speed limit down a hill when there's an uphill coming, etc)

No problem :)

And hence my argument that it will save you fuel out in Rural areas where you have the luxury of coasting for great distances, but not so good in city traffic where you are making constant adjustments.


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