Author Topic: Mpg  (Read 484 times)

Offline Worker

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Mpg
« on: 14 April 2024, 06:33 »
I have a golf gti mark 7 2019. It has done 10000 miles
I was getting up to 52 mpg for a long time and during the last 6 months this has reduced to 33 on a run driving at 55.  Driving on a regular route.  When in fifth or sixth gear it feels like it is in third gear.  In fact on a shorter run I get better mileage.  I have never experienced this before.  I have been the owner of four Gti during the last 35 years!  I have the same driving style. 
It has been checked out and no faults found
The tyres are inflated to 38.
The brakes have been cleaned
No faults show on the dash.
I am informed there is nothing wrong with it!  That they are thirsty cars!
Please could someone help me?
Thank you.


Offline Tractor Dave

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Re: Mpg
« Reply #1 on: 14 April 2024, 06:58 »
Check to see if you have a caliper sticking.
Take the car for a short drive and avoid using the brakes as much as possible. Just a few miles should be enough. Then go around and feel each brake disk (carefully) for heat. If any are really hot, you have a sticking caliper. It's very common with low mileage use.

Offline Adam T7

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Re: Mpg
« Reply #2 on: 14 April 2024, 07:22 »
MY2019 GTI Mk 7.5 Performance. DSG, 5 Door, Rear Camera, Climate Windscreen and Rear Window Factory Tints, Indium Grey.

Offline Worker

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Re: Mpg
« Reply #3 on: 14 April 2024, 08:59 »
I would like to add could it be gp regen blocked due to the short trips I make? 
Would the warning light come if this the case?
Thanks

Offline SRGTD

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Re: Mpg
« Reply #4 on: 14 April 2024, 10:03 »
I would like to add could it be gp regen blocked due to the short trips I make? 
Would the warning light come if this the case?
Thanks

GPF regeneration was my initial thought. In addition to your car feeling like it’s in a different gear to the actual gear and your poor fuel consumption, is your car displaying any of the other symptoms that might indicate a forced GPF regeneration is in progress? (See list in my post - reply #6 - at the link posted by @Adam T in reply #2 above). During a forced GPF regeneration, additional fuel is used to help raise the exhaust temperature and neutralise accumulated particulate matter. When my car (a 2020 2.0 litre Polo GTI+) is performing a forced GPF regen, the additional fuel usage results in my mpg worsening by around 30-35% until the regen has finished, after which mpg returns to normal levels.

I don’t think VW’s have a warning lamp in the instrumentation display to show when a GPF regeneration is taking place (my car certainly doesn’t) even though I think some owner’s manuals for various VAG brands might make reference to a warning lamp.

If your car is attempting to perform a forced GPF regen and you complete your your journey before it’s finished (quite likely if you’re doing a high proportion of short trips), then it’ll recommence the regen process during the next - and subsequent - ignition cycle(s) until the process is complete. Assuming that’s what’s happening with your car, then I’d recommend taking it on a decent length run so the engine can get up to optimum operating temperature and trying the ‘engine braking’ method to help clear the GPF; details in my post #6 at the linked discussion topic referred to above.

Please update this discussion topic for the benefit of other forum members once you’ve done the above.
2020 Polo GTI Plus; Pure White, DSG (because they all are)
Gone but not forgotten;
2016 Polo GTI; Blue Silk
2011 mk6 Golf GTD; Carbon Grey
2007 mk5 Golf GT (2.0 170bhp TDI version); Deep Black Pearl
2002  mk4 Golf GTI (the 150 bhp diesel version); Deep Black Pearl

Offline Watts

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Re: Mpg
« Reply #5 on: 14 April 2024, 17:17 »
Gpf regen is a distinct possibility, mine gets a noticeably noisier exhaust note too and yes, the mpg plummets. Also find the fans still running after turning the engine off. Take it for a good long run and see if that clears it. A couple of hours steady on the motorway should do it.
2019 Oryx White 5dr TCR.

Was - 2015 Tornado Red 3dr GTI PP, manual, Santiagos, Audi short shifter.

Offline Worker

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Re: Mpg
« Reply #6 on: 16 April 2024, 09:13 »
Thank you.  This is invaluable to me.  I am away until the end of the week.  I will get back to everyone when I have done what is suggested.

Offline Adam T7

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Re: Mpg
« Reply #7 on: 16 April 2024, 10:58 »
SRGTD’s advice was 100% spot on, I noticed the difference after about 10 miles.
MY2019 GTI Mk 7.5 Performance. DSG, 5 Door, Rear Camera, Climate Windscreen and Rear Window Factory Tints, Indium Grey.