Poor fuel consumption Golf Mk 7.5 GTD

[Se7enheaven]

Daily average fuel consumption has dropped dramatically over the last week from about 43 to 45 mpg for my usual 20 mile run into work ,down to about 34 to 36 . The weather is obviously particularly cold at the moment and as such my average speed is lower overall , but I would have thought if anything the mpg would have remained the same or even improved. I’m quite shocked how poor it is just now. Anyone any input as to why it may have dropped so much ? Thanks

[SteBrown91]

I have a mk7 gtd estate, and in summer I will easily average 50+mpg on my commute if I don’t drive like an arse and get a clear run. This time of year I get low 40s at best. Car high idling to warm up when cold, heating on, heated seats on, lights on etc all adds up. I’d say it’s just the very cold weather affecting you.

[halo34]

DPF could be cycling quite hard if its doing short runs. 20 miles is probably just hitting warm enough to cycle.

Maybe try a longer run as this cold weather could be holding it back from a full regen - they usually dont drop that much, but diesels do take a good few miles to warm up.

Edited by halo34 on Tuesday 13th December 21:23

[Se7enheaven]

Thanks for replies and input . I’ll give it a longer run to heat up more and see if that helps .

[Fast and Spurious]

Se7enheaven said:

Thanks for replies and input . I’ll give it a longer run to heat up more and see if that helps .

[BlindedByTheLights]

Winter diesel too, I used to always get less mpg in winter In My gtd.

[SteBrown91]

BlindedByTheLights said:

Winter diesel too, I used to always get less mpg in winter In My gtd.

Yes forgot about this, my car definitely does not run as nicely on winter diesel. Very knocky and hunts the revs on cold idle ever so slightly.

[BlindedByTheLights]

SteBrown91 said:

BlindedByTheLights said:

Winter diesel too, I used to always get less mpg in winter In My gtd.

Yes forgot about this, my car definitely does not run as nicely on winter diesel. Very knocky and hunts the revs on cold idle ever so slightly.

I agree, bit more lumpy on idle

[missing the VR6]

I suspect you're also using the AC/Heater more and probably heated seats, all additional strain on the engine. Remember asking the technicians at VW when I worked there about it, that was the response I got. Had 3 GTDS.

[cuprabob]

During the summer my VW 2.0l diesel averages 55mpg but as soon as the temps drop during the winter its more like 45mpg. Its a combination of winter diesel and the extra time it takes to heat up.

For reference it's a EA189 without the "emissions fix"

[Se7enheaven]

After few more days of running it’s evident when temp drops below about -2 that the mpg drops right off. Similar things on in car ( heated seat , heater , lights etc ) , same route , same speed. For few days I was back to the normal mpg. Temp dropped below -2 again last few days again and car is back into the mid 30’s.
I’ve had this 17 plate car for a year now , but I have to say the overall mpg is very disappointing on it. It’s a lovely car to drive but the running costs are alot higher than I expected.

[Insert Coin]

I’ve got the 204 and dsg in my van, lucky to get more than 24mpg round town and 32ish on a run.

It’s a juicy engine, not very frugal at all.

[cslwannabe]

Tyre pressures also drop with ambient temperature - check and inflate, if necessary.

[SteBrown91]

Thanks to the warm weather yesterday I got 54 to the gallon on the way home last night

[Fusion777]

You should be way over mid 30s on a 20 mile run, even in the depths of winter. Driving style? When was it last serviced? What tyre pressures are you running?

[Se7enheaven]

Fusion777 said:

You should be way over mid 30s on a 20 mile run, even in the depths of winter. Driving style? When was it last serviced? What tyre pressures are you running?

Yep , it’s a severe drop in fuel economy which to me is not really explained within a few degrees of temp. Car is well serviced , tyre pressures correct , same steady driving style , same route , same power draw regarding lights , heated seat etc. Above about -2 the car will average mid 40’s but as soon as temp drops below that the mpg drops drastically. I’ve been driving for a long time and in all my years of driving and experience have I seen such a change.
Sorry VW but I ain’t impressed.

[BlindedByTheLights]

Our 2019 vw 2.0tdi was struggling to get above 40mpg last week and that was on a decent run mostly sat at 70. Yesterday it was getting 55mpg and oddly that was with a lot more stop start and slower speeds. So the cold does seem to affect them a lot.

[Fusion777]

I've got a 2010 Golf 2.0 TDI 140ps (manual), EA189. My commute is just over 18 miles and I don't think I've ever seen below 46mpg (on board computer), either way, even in the recent cold snap. A lot of that is steadyish dual carriageway cruising though.

Best I've seen on that run one way is 66mpg, but that's in warmer weather. I pretty much always use V-Power.

Edited by Fusion777 on Tuesday 20th December 17:41

[Belle427]

How does your temp gauge behave in the cold conditions?
Vag diesel cars in my experience always sit at 90 degrees until it gets very cold then start to drop slightly lower.
Maybe this contributes to extra fuel being added?
Just a wild guess.

[BlindedByTheLights]

Belle427 said:

How does your temp gauge behave in the cold conditions?
Vag diesel cars in my experience always sit at 90 degrees until it gets very cold then start to drop slightly lower.
Maybe this contributes to extra fuel being added?
Just a wild guess.

Just sits at 90, never moves, oil at between 90-102ish