To Coast or Not To Coast.......

[Stuarty]

Hiya,

That's me had my Cali for a couple of months now! Delighted with her, but still really working my way through everything......

I was just wondering what people's thoughts were regarding the DGS coast function. It came turned on with the Cali, but I couldn't get used to it when driving it home from the dealer, so I turned it off. I just felt that any engine braking functionality was then gone when going down hills. TBH, even with the coast function off, I've noticed a difference between the DSG box and the manual box I had on my last van. There seems to be a big jump from 4th down to 3rd. Anyway, that's a different question.

Do you guys think the coasting option is good or not? I've created a wee poll to see what people are doing with this. I can maybe see where it would be useful on long flat motorways, but the roads I drive are mainly single carriageway, hilly A or B roads.

Cheers in advance for any advice.

 

[Lewis]

Use it every day on downhill stretches. Since making a conscious effort to use it properly I've noticed a good bump in fuel economy. Takes a bit of getting used to and my OH rarely remembers but I like it

 

[ArunAlec]

I use mine and rarely notice that it's coasting. Being of an age where I was taught to use the engine to help braking the concept of coasting was a bit alien but I think modern day thinking is to rely on modern efficient brakes. Also the coasting drops out as soon as you touch the brakes so you can easily "regain control" when you need to.

 

[Zenaj]

I found coasting very good and useful. Going downhil just tap the brake to disable coasting and engage engine braking. Than tap acceleration pedal to coast again. I like it.


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[T6 CFO]

If you'd asked me before I tried it I would have had doubts as effectively rolling along in neutral was always a bad idea.
Coasting though is different all it requires is the merest touch on the brake to enable engine breaking and to enable a touch of and then lift off the throttle. Use it all the time.

Mike


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[Jabberwocky]

Its kind of the opposite to cruise control. If you never experienced it, it will take you a while to get used to but then it becomes second nature. I've had my Cali for three months now and keep the coast function switched on. Just be aware that a three ton + Cali can run off downhill quite quickly!

 

[briwy]

Why would it make a difference to fuel consumption?
The engine is still running and my understanding is that if foot is off the accelerator then the engine is using same as tick over.
I thought it was actually illegal to coast. Certainly used to be years ago, must have changed.

 

[Zenaj]

Because it's accelerating by the use of gravity force instead of fuel (going downhill). And because no gear is engaged while coasting, hence no engine braking. I think.


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[briwy]

Google search, one of many saying the same thing. Aplies to both diesel and petrol.

"There are two situations. Situation one: the engine is running at idle speed, the gearbox is in neutral or the clutch is disengaged. Then the engine needs some fuel to keep running. This amount is approximately 4 litres per hour. The other situation: The car is running at a certain speed, let's say 50 mph, the gearbox is in 4th gear, the clutch is engaged. Now you lift your foot off the accelerator. The fuel consumption drops to zero immerdiately. The engine does not need any fuel to keep on revving, because the moving car drives the engine. In this situation you will feel a considerable amount of deceleration. This is called "engine brake". Somewhere in the 80s all car manufacturers began to install idle control valves into the carburettors of the engine, which detect such an "engine brake" situation and cut off fuel supply completely. They open the fuel supply again as soon as the engine revolution speed drops to a certain level (the idle speed).

Today most car engines have fuel injection systems. They behave similar. Diesel engines never had Carburettors and they never burned fuel during "engine brake".

If you want to drive as fuel efficient as possible, you should avoid letting your car roll for a longer distance without a gear engaged, because the engine needs fuel for revving as soon as it is not driven by the rolling car."

 

[hirsty]

You've got too much free time your hands - coast is a no brainer, as is Stop/Start FWIW.

If you're on hilly B-roads stick it into manual or Sport.

 

[briwy]

Well mines a manual thank god so we don't have the Coast function. Still not answered the question though.

 

[WelshGas]

Well mines a manual thank god so we don't have the Coast function. Still not answered the question though.

https://www.autocar.co.uk/opinion/green-cars/sometimes-it-preferable-coast-through-life

http://en.volkswagen.com/en/innovation-and-technology/technical-glossary/freilauffunktion.html

https://vwcaliforniaclub.com/threads/engine-brake-dsg.12410/

 

[Romke]

In the seventies I drove Saabs 95 and 96 which had a freewheel switch. I loved it! Our new Cali (due later this year) will have a DSG and I'm sure I'll love the Coast function there as well. And by the way: our Cali will be a Coast so that means double coasting for us!

 

[Stuarty]

Hi all,

Thanks for all your responses. Looks like the vote for coasting is winning!
Just a quick note on the engine braking vs mechanical braking question. Any driving courses I have done (both car and motorbike) have always preferred us to use engine braking, with the brakes only being applied if it was absolutely necessary. When sitting advanced driving tests, I think you can fail for too much use of the brakes. I think the theory is that it places more wear and tear on the vehicle, and by effectively using engine braking and not relying on the mechanical brakes all of the time you are demonstrating that you are reading the road conditions and anticipating what you are coming up to better. It was also supposed to be better for fuel economy.
Maybe that theory is a bit out of date now though. Must look into it and let you know.
Cheers.

 

[Stuarty]

Thanks for pointing us in the directions of the articles WelshGas!

 

[Bellcrew]

Hi all,

Thanks for all your responses. Looks like the vote for coasting is winning!
Just a quick note on the engine braking vs mechanical braking question. Any driving courses I have done (both car and motorbike) have always preferred us to use engine braking, with the brakes only being applied if it was absolutely necessary. When sitting advanced driving tests, I think you can fail for too much use of the brakes. I think the theory is that it places more wear and tear on the vehicle, and by effectively using engine braking and not relying on the mechanical brakes all of the time you are demonstrating that you are reading the road conditions and anticipating what you are coming up to better. It was also supposed to be better for fuel economy.
Maybe that theory is a bit out of date now though. Must look into it and let you know.
Cheers.

In the days when vehicles used drum brakes engine braking was not only good practice but often a necessity to avoid loss of brake efficiency, with ventilated discs not so much.

 

[WelshGas]

Hi all,

Thanks for all your responses. Looks like the vote for coasting is winning!
Just a quick note on the engine braking vs mechanical braking question. Any driving courses I have done (both car and motorbike) have always preferred us to use engine braking, with the brakes only being applied if it was absolutely necessary. When sitting advanced driving tests, I think you can fail for too much use of the brakes. I think the theory is that it places more wear and tear on the vehicle, and by effectively using engine braking and not relying on the mechanical brakes all of the time you are demonstrating that you are reading the road conditions and anticipating what you are coming up to better. It was also supposed to be better for fuel economy.
Maybe that theory is a bit out of date now though. Must look into it and let you know.
Cheers.

That's what I was taught, in the way distant past, but my wife took a Motorway refresher cause recently with a very highly recommended instructor who also does Advanced Driving, HGV and Police and Ambulance courses and he said with the advent of Auuto boxes and multi gear boxes, such as HGV 32 gears, the primary mode of slowing is brakes. Yes, you anticipate to be in the correct gear but just backing off on the gas and changing down to use engine braking is not always sufficient. E.g.: if taking a motorway slip road you should only slow when on the slip road to avoid emergency braking of vehicles behind and this may give insufficient room to slow down through the gears, especially in auto boxes, so braking is necessary. Also modern gear boxes are much more expensive than the older 4 speed especially compared to brake pads. Modern brakes are much less susceptible to brake fade in normal driving.
Would be interesting to know what you find out.

 

[briwy]

On the way down to Brean today I knocked out van out of gear (manual) and the display showed 200mpg. Then took my foot of down a rise and the display showed nothing, presumably indicating no fuel being used.
Perhaps the DSG is different but for my money with a manual coasting would appear to use more fuel not less.

 

[WelshGas]

On the way down to Brean today I knocked out van out of gear (manual) and the display showed 200mpg. Then took my foot of down a rise and the display showed nothing, presumably indicating no fuel being used.
Perhaps the DSG is different but for my money with a manual coasting would appear to use more fuel not less.

And when you put it back into gear you have to get the correct gear, correct engine speed otherwise you will put undue strain on the gearbox and/clutch. With the DSG Coast function the DSG clutch is disengaged and the engine idles. While Coasting the road speed is monitored and the DSG box changes to the appropriate gear. When the accelerator or brake is pressed the engine speed is increased to the appropriate revs so that the DSG clutch is engaged seemlessly with NO additional strain. VW claim a saving of 0.5L/100 km.
After driving up and down the Lofoten Islands with extensive use of the Coast function I was surprised to see that my fuel consumption had improved by 1.5 mpg. I expected the reverse with the road terrain I encountered.
Comparing Coasting in a manual to a DSG box is like comparing chalk and cheese. Totally different systems.

I'm not sure what you are saying with your statement. Yes, on idle you use fuel. So in Neutral on a manual or Coast on a DSG the engine is idling and using fuel.
Using engine braking, foot off accelerator, in a Manual no fuel used, exactly the same in a DSG.
In fact what you should be comparing is a Manual on an undulating road, either accelerator depressed or not, hence engine braking, whereas the DSG can have accelerator depressed, idle or engine braking and with a bit of practice it becomes second nature.

 

[B J G]

Coasting isn't illegal. When taking a driving test excessive coasting can lead to fail as it is deemed that the vehicle isn't under full control.
Not found any information as to Police view if an accident occurred whilst vehicle in coast mode.

I have now stopped using the coast function for everyday driving for the following reasons. I would still use it on a scenic run when conditions and the road would make it possible.

1. No engine brake, leading to closing within legal distance of traffic ahead

2 No speed loss when entering a speed limit area. Potential points & fine.

3 Can gain speed on down hill sections again risking speeding fines.

4 Need more use of brakes which will wear and are expensive items. Discs & pads.

5 Little engine water cooling due to low revs.

6 Following vehicles have to put up with flashing brake lights due to you disengaging coasting.

7 If a good system why does't cruise use it?

Cat amongst pigeons now comes to mind.

 

[Pure Worktop Protection]

Been using Coast on our 204 DSG since it arrived in January and think it's really good - my run into work is mainly downhill and get 43 mpg using coast, sadly 29mpg on the return trip.!
However when I first got the Cali it used to show "coasting" on the dash when activated but it no longer shows - any ideas?

 

[T6 CFO]

Coasting isn't illegal. When taking a driving test excessive coasting can lead to fail as it is deemed that the vehicle isn't under full control.
Not found any information as to Police view if an accident occurred whilst vehicle in coast mode.

I have now stopped using the coast function for everyday driving for the following reasons. I would still use it on a scenic run when conditions and the road would make it possible.

1. No engine brake, leading to closing within legal distance of traffic ahead

2 No speed loss when entering a speed limit area. Potential points & fine.

3 Can gain speed on down hill sections again risking speeding fines.

4 Need more use of brakes which will wear and are expensive items. Discs & pads.

5 Little engine water cooling due to low revs.

6 Following vehicles have to put up with flashing brake lights due to you disengaging coasting.

7 If a good system why does't cruise use it?

Cat amongst pigeons now comes to mind.

It's all down to opinions at the end of the day. With coast activated you can still decide by a flick of the right boot if you wish to deactivate it. It's like ACC or most other aids, you need to know how it works and only use it when the circumstances are right.

Mike

 

[T6 CFO]

Been using Coast on our 204 DSG since it arrived in January and think it's really good - my run into work is mainly downhill and get 43 mpg using coast, sadly 29mpg on the return trip.!
However when I first got the Cali it used to show "coasting" on the dash when activated but it no longer shows - any ideas?

On mine D on its own in top right hand corner shows it's in Coast. Then obviously D1 D2 etc etc shows the other gears.

Mike

 

[Teejay]

Been using Coast on our 204 DSG since it arrived in January and think it's really good - my run into work is mainly downhill and get 43 mpg using coast, sadly 29mpg on the return trip.!
However when I first got the Cali it used to show "coasting" on the dash when activated but it no longer shows - any ideas?

I'm sure that has something to do with what you are displaying on the MFD.

..me..

 

[WelshGas]

Coasting isn't illegal. When taking a driving test excessive coasting can lead to fail as it is deemed that the vehicle isn't under full control.
Not found any information as to Police view if an accident occurred whilst vehicle in coast mode.

I have now stopped using the coast function for everyday driving for the following reasons. I would still use it on a scenic run when conditions and the road would make it possible.

1. No engine brake, leading to closing within legal distance of traffic ahead

2 No speed loss when entering a speed limit area. Potential points & fine.

3 Can gain speed on down hill sections again risking speeding fines.

4 Need more use of brakes which will wear and are expensive items. Discs & pads.

5 Little engine water cooling due to low revs.

6 Following vehicles have to put up with flashing brake lights due to you disengaging coasting.

7 If a good system why does't cruise use it?

Cat amongst pigeons now comes to mind.

1. That depends on the competence of the driver.

2. That depends on the competence of the driver.

3. That depends on the competence of the driver.

4. Compared to the cost of a gearbox/clutch modern brake pads and discs are cheap.

5. The California uses Electric Fans and anyway a Diesel engine has problems keeping warm.

6. Unless actually braking the Coast function can be disabled by moving the brake peddle a few mm's without activating the brakes themselves and hence the rear brake lights. Separate pressure activated switch for brake lights.

7. You can if you wish.