2019 GTI - fuel consumption

[westenderbender]

Hey all

I’ve got a 2019 GTI with 13,000 on the clock. It used to get around 5.8L/100km on the freeway right up to about 10,000km. These days I’m lucky to get dip under 7.0L/100km.

The only change I’ve made to the car was replacing the stock 18s/Bridgestone S001s with the Brescia 19s/Michelin PS4S in February.

Surely this wouldn’t change fuel consumption so much?

Anyone have any ideas or experienced anything similar?

Other thoughts I had were tyre pressure, and switching to exclusively filling up at my local franchise BP....

Cheers

[phaeton]

Different wheel circumference will definitely alter the computer readout speed, fuel consumption, etc.

[westenderbender]

Different wheel circumference will definitely alter the computer readout speed, fuel consumption, etc.

Yeah I wondered that, but the dealer said it makes no difference when I took it for a service last week. Plus I have been checking the computer readout by manually calculating consumption, and it’s bang on.

So the models have different computer settings from factory based on which wheels they have?

[gregozedobe]

The PS4S tyres might have more rolling resistance than the S001s, but I wouldn't expect it to have a big affect.

What tyre pressure are you running ?

Cooler weather increases fuel consumption (as does rain, heavy traffic, higher speeds, more weight in car, driving styles etc)

Have you changed brands of petrol ? Anything with ethanol will use more fuel.

Most people find fuel consumption decreases (very) slightly when the car gets properly run in.

[westenderbender]

Yeah I was expecting it to keep dropping but it’s stubbornly sitting at 7.0 on identical drives that used to go down to 5.8.

I’ll try a different petrol station in case my local BP waters down their 98 lol

Running 41 psi all round

[bor1203]

I thought that it could be the width increase of the tyres (225 to 235?) that would affect fuel consumption. Surprised it would be that noticeable though


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[ABCD]

Probably combination of increased rolling resistance from more rubber on road with the extra width, a stickier rubber compound and ? more toe-in from the wider wheels.

[westenderbender]

2019 GTI - fuel consumption

Thanks for the comments.

Anybody here run the 2019 GTI with 19 wheels? What sort of consumption do you get?

(Note that my 5.8 on the 18s was achieved regularly at 110km/hr, the equivalent driving on 19s is getting me 7.0)

Side note: this isn’t any sort of complaint with the car, 7L/100km is still bloody good, was just curious if a setting needed to be adjusted or if there was an increase from running the Michelins

[rosslm]

Thanks for the comments.

Anybody here run the 2019 GTI with 19 wheels? What sort of consumption do you get?

(Note that my 5.8 on the 18s was achieved regularly at 110km/hr, the equivalent driving on 19s is getting me 7.0)

Side note: this isn’t any sort of complaint with the car, 7L/100km is still bloody good, was just curious if a setting needed to be adjusted or if there was an increase from running the Michelins

My Golf R stock Pretoria 19" 235/35/19 ContiContactSport 5P will return around +/- 6L /100km at 110km freeway cruise that's with DQ381 7 speed DSG if that helps, check wheel alignment I cannot see the change of wheel/tyres having a +1 l/100km difference.

[gregozedobe]

If you still have the old wheels & tyres it would be interesting to put them back on to eliminate the change in wheels as the cause for the increase in fuel consumption.

BTW 41psi seems a bit high for a GTI. I run 36psi all round on my heavier Golf R wagon.

[westenderbender]

My Golf R stock Pretoria 19" 235/35/19 ContiContactSport 5P will return around +/- 6L /100km at 110km freeway cruise that's with DQ381 7 speed DSG if that helps, check wheel alignment I cannot see the change of wheel/tyres having a +1 l/100km difference.

Good idea on the wheel alignment. When I got the Michelins and 19s put on, they were meant to have done an alignment. But they also had all 4 tyres at very different PSI (from 33 up to 39), so they may have screwed the alignment too.

I was going to wait til my 1st service last week before investigating the issue, in case an oil change fixed it. They recommended a wheel alignment but thought it was just an up-sell.

[westenderbender]

If you still have the old wheels & tyres it would be interesting to put them back on to eliminate the change in wheels as the cause for the increase in fuel consumption.

BTW 41psi seems a bit high for a GTI. I run 36psi all round on my heavier Golf R wagon.

Nah sold them, couldn’t bear to look at them any longer haha

[mkrugs]

If you have changed wheel circumference then your consumption will be the same but consumption will measure differently on the read out as each rotation affects the distance.

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[bor1203]

If you have changed wheel circumference then your consumption will be the same but consumption will measure differently on the read out as each rotation affects the distance.

The change in circumference is just 1.6% though from 225/40/18 to 235/35/19. There are websites you can compare changes between tyre sizes


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[westenderbender]

Well I’m going to try a different servo to my usual BP next refill (which I’ve been going to almost exclusively since around the same time as the wheel change).

Let’s see if that makes a difference. Small chance, but if it goes back to normal then I can deduce that it’s a dodgy servo.