Fuel consumption

[MikeDO]

Facelift GTI coasts in normal mode as well as eco.

[funkyg]

Facelift GTI coasts in normal mode as well as eco.

Really? That's a terrible idea! I've tried the Eco mode in my pre-facelift GTI and it's very unnerving. It feels like you don't have full control of the car while it's coasting, when all my driving life you lift off the acceleator you start to slow down...not in Eco! I guess you'd get used to it but I don't like it. Similar to 'one pedal driving' in electric cars - it just feels wrong!

[PoloGTInoob]

From what I’ve read on other forums, Eco mode also;

• dulls the throttle response, requiring the accelerator pedal to be pressed harder to get up to cruising speed and for manoeuvres such as overtaking. So IMHO, any potential mpg gains to be had from the coasting function could possibly be negated by heavier use of the throttle…………….

im quite trigger happy with switching the driving modes. On a 1hr journey, i might rotate between individual and eco mode 5 - 10 times. Using eco mode when cruising on A roads so i can benefit from coasting, and switching to normal/individual mode at other times when i might need to accelerate more rapidly. Each to their own though, im sure most people dont want to do this switching but i like to adapt the car's electronics to suit my driving style

i also default the auto stop/start mode to OFF and turn it back on when i know ill be stopping for a while.

when i have passengers, they wonder WTF im dong all the time with these buttons

[MikeDO]

Facelift GTI coasts in normal mode as well as eco.

Really? That's a terrible idea! I've tried the Eco mode in my pre-facelift GTI and it's very unnerving. It feels like you don't have full control of the car while it's coasting, when all my driving life you lift off the accelerator you start to slow down...not in Eco! I guess you'd get used to it but I don't like it. Similar to 'one pedal driving' in electric cars - it just feels wrong!

The car only "coasts" under very specific circumstances (IE. usually when under low load and on the flat). The second you touch the throttle the gearbox engages. Seems to work pretty well to me. You very soon get used to it.
Not sure if the "coasting" function is in anyway re-programed compared to pre-facelift models!?

I tend to knock the gear selector back into sport mode for overtaking and pulling into fast moving traffic, as the car does have a tenancy to change up a gear on the slightest lift of the throttle.
But we all have our different ways of driving etc. I suppose.

[Johntheo1]

Does the engine stay running while coasting??, if so wonder how much saving is achieved vs the normal where the fuel injection ceases from > than ~ 1600rpm down to ~ 1000rpm, (with accelerator released)

[MikeDO]

Does the engine stay running while coasting??, if so wonder how much saving is achieved vs the normal where the fuel injection ceases from > than ~ 1600rpm down to ~ 1000rpm, (with accelerator released)

Engine just drops back to "tick over" when it coasts.

Probably doesn't make a HUGE difference, but every little helps on a longer journey.

One of the things that I like about the GTI, is that while the performance is there when you want it, it is also capable of some more than reasonable economy. The best of both worlds in my opinion.

[SRGTD]

Does the engine stay running while coasting??, if so wonder how much saving is achieved vs the normal where the fuel injection ceases from > than ~ 1600rpm down to ~ 1000rpm, (with accelerator released)

Engine just drops back to "tick over" when it coasts.

Probably doesn't make a HUGE difference, but every little helps on a longer journey.

One of the things that I like about the GTI, is that while the performance is there when you want it, it is also capable of some more than reasonable economy. The best of both worlds in my opinion.

I read an article recently that quoted potential fuel savings that might be realised in practical use with a mk7.5 Golf hybrid with DSG transmission as a result of the coasting function. In that car, the engine was completely switched off / deactivated rather than idling when coasting. The article quoted two figures;

- coasting with the engine completely deactivated; 0.4 litres per 100 km
- coasting with the engine idling; 0.2 litres per 100 km.

Link to that article; https://www.vwpress.co.uk/en-gb/releases/2922

So with the Polo’s engine running at idle speed while coasting, the second of the above two figures would probably be more representative of potential fuel savings that might be realised in the Polo, but it should be borne in mind that driving style will also be a significant factor in actual savings realised. Converting km’s to miles (100 km = 62 miles), that would equate to fuel savings of 3.2 millilitres per mile.

So with my ‘back of a fag packet’ calculations to put the above potential fuel savings into some sort of context;

• If a 1.0 litre Polo is able to achieve an average fuel consumption of 55mpg (guesstimated) over a tankful of fuel (Polo tank size = 40 litres / 8.8 gallons), that would equate to a fuel saving per tankful of 1.55 litres (3.2 millilitres x 484 miles driving range) or £2.17 per tankful based on an assumed fuel price of £1.40 per litre.

• Similarity, for a GTI, assuming an average fuel consumption of 43mpg (which is roughly the long term average mpg in my GTI+), fuel savings would a be 1.21 litres per tankful (3.2 millilitres x 378 miles driving range) or £1.69 per tankful based on an assumed fuel price of £1.40 per litre.

Above ‘fag packet’ calculations don’t allow for the Golf being a larger / heavier car, but in the grand scheme of things, monetary savings would be small.

The cynic in me would say that VW weren’t really considering fuel savings when introducing the coasting function - their primary objective would have been to improve vehicle emissions. Motor manufacturers are fined if the average emissions of their entire fleet of new vehicles available for sale exceeds the current EU target of 95g CO2 per km. A 1.0 litre 110ps Polo with DSG has a quoted CO2 emissions figure of 123g per km, so most - if not all - of the ICE vehicles in VW’s fleet will exceed the EU target figure. A significant proportion of VW’s overall vehicle sales would need to be EV or hybrid for the fleet average CO2 figure to meet or better the emissions target, so VW could avoid paying emissions fines / penalties .

[grazuncle2]

most likely!

many of the so-called performance and economy figures are massaged..

take the so-called urban cycle... (which stands for Un Reachable Bluff And Nonsense) have been found to be highly optimised right down to optimum fuels, tyres and pressures, payload and terrain etc etc. no typical to most people and hence meaningless except to he boffins.

If think anticipation and the weight of your right foot has the most significance.. LOL

[SRGTD]

most likely!

many of the so-called performance and economy figures are massaged..

take the so-called urban cycle... (which stands for Un Reachable Bluff And Nonsense) have been found to be highly optimised right down to optimum fuels, tyres and pressures, payload and terrain etc etc. no typical to most people and hence meaningless except to he boffins.

If think anticipation and the weight of your right foot has the most significance.. LOL

Agree - one short burst of enthusiasm with a heavy right foot, or the need for frequent braking through failure to anticipate road conditions or the actions of others, is likely to negate the potential few millilitres of fuel savings derived from the coasting function.

[PoloGTInoob]

most likely!

many of the so-called performance and economy figures are massaged..

take the so-called urban cycle... (which stands for Un Reachable Bluff And Nonsense) have been found to be highly optimised right down to optimum fuels, tyres and pressures, payload and terrain etc etc. no typical to most people and hence meaningless except to he boffins.

If think anticipation and the weight of your right foot has the most significance.. LOL

Agree - one short burst of enthusiasm with a heavy right foot, or the need for frequent braking through failure to anticipate road conditions or the actions of others, is likely to negate the potential few millilitres of fuel savings derived from the coasting function.

Exactly. Annoys when driving on a nice A road and all the cars are bunched up a few metres behind each other constantly braking and re-accelerating, while i leave a nice distance so i can anticipate and not need to brake.

[grazuncle2]

Exactly. Annoys when driving on a nice A road and all the cars are bunched up a few metres behind each other constantly braking and re-accelerating, while i leave a nice distance so i can anticipate and not need to brake.

.. and hope no idiot thinks he can squeeze in that space and gain a single spot, 5 yrds further up the que!

I get this often on motorways.. leave a sensible gap and someone shoehorns their way in...