mpg has dropped since service!

vikingaero

ianbar0 wrote: »

yeah might have to have a look at what they have done! thought it was not anything major. as for the mpg before, its basically all downhill to work hense i would hope i was getting 70mpg! especially with over a mile of coasting! i think they may have messed something when plugged in, its odd because while the trip computer is reading very different im not sure the fuel pointer is moving as same new rate.

How do you get back up? Push it?

I doubt you'll get a realistic 70mpg in a Golf on a short commute with a new, tight engine.

There are normally other factors at this time of year: cold weather = more time running rich, darker mornings and nights = air con/demist/rear window heaters etc, and a slight change in the formulation of diesel to prevent in freezing in the winter.

Maybe you overinflated your tyres, giving rise to the super mpg, and the garage simply adjusted the air to the correct psi?

anotherbaldrick

I have found the computer mpg readings on both my present and previous Golfs to be very accurate. Remember if you have just had a service the oil will be new and the viscosity a bit more, this will drag the engine for a few weeks until it weathers.

ianbar0

anotherbaldrick....thank you will keep that in mind, i did think tonight about the oil so thank you for that.

ianbar0

i don't know why people think i have not got 70mpg at times? i know its high, my commute is at 9.40 on a night so no traffic, its pretty much all downhill i would say i only need to use the gas 1/3 of the distance! the diesel issue may be a case, bt have not needed to put any air in tyres since i bought her. plus its not really that cold yet and certainly not in the last week. i do wonder about the oil out of what people have said so will see. i won't be rushing too garage as she is running fine otherwise, and by time she goes back in week or so the issue may have ran itself out anyway

27col

I think that you will find that it is not only illegal to coast downhill, but also quite dangerous. My car tells me that it is doing 99.9mpg when in cruise control and running down a slight incline. But it is always in gear, while in cruise mode.

vikingaero

ianbar0 wrote: »

i don't know why people think i have not got 70mpg at times? i know its high, my commute is at 9.40 on a night so no traffic, its pretty much all downhill i would say i only need to use the gas 1/3 of the distance!

You seem to be fixated on the downhill issue. Yes you may have a large downhill element of your commute, but you will use far far more than you've saved in going back home uphill. Even if you use a different route home you'll still have to spend some time going back up on a decent amount of throttle.

vaio

vikingaero wrote: »

You seem to be fixated on the downhill issue. Yes you may have a large downhill element of your commute, but you will use far far more than you've saved in going back home uphill. Even if you use a different route home you'll still have to spend some time going back up on a decent amount of throttle.

Don't know how mentioning it turns into "fixated", and the OP even managed to spot your point about uphill trips being more expensive than down hill trips to the point that it was mentioned in the OP together with results for both legs

ianbar0 wrote: »

..... i can do nearly 70mpg and back just over 50mpg but this week i have been down to less than 50mpg there and 30 odd on way back......

Alexis27

Are you only doing 3 miles to work and back again every day? And a lot of it is downhill with no throttle?

Diesels are not designed for such short runs. The particulate filter will clog in no time and your MPG capability will decrease. You need to take it out for a long run at least once a week and work the engine.

DUTR

vaio wrote: »

Presumably the OP doesn't service the car themselves because of warranty, ability or choice reasons but that doesn't alter the fact that from the factory the display said 70 and after the service it now says 50 and it doesn't seem unreasonable to ask why.

I agree, except for the ability bit, but as others have mentioned what the display shows is not always correct, I had loan of an A3, just getting it out of the garage it would show >50mpg which is obviously incorrect, my golf would show something like 12mpg, but would increase as you execute the journey, the difference the OP notices on the display is more likely that it is now showing a more realistic figure.

Nilrem

DUTR wrote: »

I agree, except for the ability bit, but as others have mentioned what the display shows is not always correct, I had loan of an A3, just getting it out of the garage it would show >50mpg which is obviously incorrect, my golf would show something like 12mpg, but would increase as you execute the journey, the difference the OP notices on the display is more likely that it is now showing a more realistic figure.

Aye, it could be part of the service included an update to the trip computer to sort out unrealistic readings (I'd imagine the software possibly gets tweaked from time to time like most software to fix bugs such as the errant massive over readings you hear about at times).


Op, did you ever do a MPG based on fuel useage when filling up?
Or just by what the trip computer estimates?
Have you noticed that after filling the car up fully you're having to refill it sooner?

I reset the trip computer for my car every time I fill it up, then divide that by the amount of fuel put in = real MPG over time that can be compared from one month to the next (in my case the MPG has barely budged in 7 years), unfortunately it's not "real time", just based on how much fuel I've put in* and the distance covered (the only real way to work it out).


*Based on litres/gallons put in, not price (something that I've seen people complain about is "my car doesn't go as far on a tenner since I had it serviced"...).