Driver Profile Selection - Coasting Function

[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]

Coasting finction in Normal Mode

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]

Coasting feature on the MY16 Golf 7

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

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.