Fuel economy..

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Potsy
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Fuel economy..

Post by Potsy » Mon Apr 01, 2019 11:02 am

Did my first decent drive yesterday, 200+ miles and returned around 40mpg from my 1.5 petrol auto.

Mix of motorway and A roads.

My 1. 4 golf would have been closer to 50mpg, albeit a manual.

Is this about right?
T Roc SE
1.5 TSI DSG
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Barnaclebob
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Re: Fuel economy..

Post by Barnaclebob » Mon Apr 01, 2019 12:18 pm

Last week I did a similar run of just over 200 miles and also returned around 40 mpg; so yes, it does seem to be average. Compared to my last car (a Tiguan 2.0 TDI) it is a bit less than I expected for a long run. The only compensation, as such, is that petrol is a good 10 pence per litre (45 pence per gallon) less than diesel at the moment...
In another thread on here we discussed the use of the Eco Mode... On my next long run I intend to use that mode - now that I’m fully aware of the foibles of using it on the T-Roc...
T-Roc, SEL, 1.5 TSI, DSG, Indium Grey Metallic,
Winter Pack, Electric Tailgate.
Ordered 04-Mar-2019.
Bought 20-Mar-2019.

Potsy
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Re: Fuel economy..

Post by Potsy » Mon Apr 01, 2019 2:50 pm

Thanks Bob.

I did notice the 'long term' average was only 34 mpg, that was from the miles before I got the car.

Have now reset this so will see how it goes over the next few months.
T Roc SE
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Impala
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Re: Fuel economy..

Post by Impala » Mon Apr 01, 2019 3:27 pm

Potsy wrote:
Mon Apr 01, 2019 11:02 am
Did my first decent drive yesterday, 200+ miles and returned around 40mpg from my 1.5 petrol auto.

Mix of motorway and A roads.

My 1. 4 golf would have been closer to 50mpg, albeit a manual.

Is this about right?
Potsy, the difference between your Golf and T-Roc is probably mostly due to new WLTP regulations.

It has been discussed and speculated in other topics on the forum that the fuel consumption figures shown in the trip computer have now to reflect the 'real world' WLTP figures, which are generally lower than the previous figures.

I suspect your Golf is a pre-WLTP car, whereas if your T-Roc was registered after 1st September 2018 it is WLTP approved.

The table below shows the difference between pre and post WLTP T-Rocs and your 40mpg looks about spot on.

For comparison, my own Golf 1.4 TSI 140PS DSG has returned an average 42.6mpg over 27,000 miles with the best tankfull returning 49mpg and the worst 36mpg, but the trip computer always shows better figures.

1.5 TSI MPG.jpg

1.5 TSI DSG R-Line Indium Grey, rear view camera, park assist.
Ordered 22/06/18
Built w/c 25/03/19 :(
With dealer 13/05/19 :P
Collected 20/05/19 :D

ianchelt
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Re: Fuel economy..

Post by ianchelt » Mon Apr 01, 2019 5:11 pm

Potsy wrote:
Mon Apr 01, 2019 11:02 am
Did my first decent drive yesterday, 200+ miles and returned around 40mpg from my 1.5 petrol auto.

Mix of motorway and A roads.

My 1. 4 golf would have been closer to 50mpg, albeit a manual.

Is this about right?
Hi - Similar figures to my 1.5Tsi DSG. I did a nice long run from Gloucstershire to Dorset over the weekend. 240 mile round trip with about 160 miles on the M5 and the rest on country roads. Returned a average 45mpg on the car's computer. Did a similar journey last year in my wife Golf 1.4Tsi and return about 58mpg.

Average mpg round town varies between 28mpg on a very short 4 mile run to the gym and 35mpg on a 16 mile run...

Impala may be right about the WLPT input into calculating "mpg" because these figures are vastly different. I am hoping that when the engine "wears in" mpg figures will improve. Only time will tell.

Cheers

T-Roc 1.5Tsi SE + Roo ;)

fez74uk
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Re: Fuel economy..

Post by fez74uk » Mon Apr 01, 2019 8:12 pm

Impala wrote:
Mon Apr 01, 2019 3:27 pm
Potsy wrote:
Mon Apr 01, 2019 11:02 am
Did my first decent drive yesterday, 200+ miles and returned around 40mpg from my 1.5 petrol auto.

Mix of motorway and A roads.

My 1. 4 golf would have been closer to 50mpg, albeit a manual.

Is this about right?
Potsy, the difference between your Golf and T-Roc is probably mostly due to new WLTP regulations.

It has been discussed and speculated in other topics on the forum that the fuel consumption figures shown in the trip computer have now to reflect the 'real world' WLTP figures, which are generally lower than the previous figures.

I suspect your Golf is a pre-WLTP car, whereas if your T-Roc was registered after 1st September 2018 it is WLTP approved.

The table below shows the difference between pre and post WLTP T-Rocs and your 40mpg looks about spot on.

For comparison, my own Golf 1.4 TSI 140PS DSG has returned an average 42.6mpg over 27,000 miles with the best tankfull returning 49mpg and the worst 36mpg, but the trip computer always shows better figures.

1.5 TSI MPG.jpg
That’s interesting that as I’ve got a 16 plate Kadjar 1.5 D and was getting a good 48 around town and about 63 on motorway journeys, it’s been for it’s mot and service and was told it had a recall for the onboard computer and infotainment system, now the fuel economy has gone way down to 36 around town and 55 on motorway I’ve rang them to find out why it’s suddenly dropped that much.
1.5 R Line DSG in Ravenna Blue.
Ordered 11/1/19
Confirmed build date 22/4/19
Notified it was built 15/4/19
In transit 23/4/19
Arrived in the uk 11/5/19
Collected 07/06/19

Impala
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Re: Fuel economy..

Post by Impala » Mon Apr 01, 2019 9:20 pm

fez74uk wrote:
Mon Apr 01, 2019 8:12 pm
Impala wrote:
Mon Apr 01, 2019 3:27 pm
Potsy wrote:
Mon Apr 01, 2019 11:02 am
Did my first decent drive yesterday, 200+ miles and returned around 40mpg from my 1.5 petrol auto.

Mix of motorway and A roads.

My 1. 4 golf would have been closer to 50mpg, albeit a manual.

Is this about right?
Potsy, the difference between your Golf and T-Roc is probably mostly due to new WLTP regulations.

It has been discussed and speculated in other topics on the forum that the fuel consumption figures shown in the trip computer have now to reflect the 'real world' WLTP figures, which are generally lower than the previous figures.

I suspect your Golf is a pre-WLTP car, whereas if your T-Roc was registered after 1st September 2018 it is WLTP approved.

The table below shows the difference between pre and post WLTP T-Rocs and your 40mpg looks about spot on.

For comparison, my own Golf 1.4 TSI 140PS DSG has returned an average 42.6mpg over 27,000 miles with the best tankfull returning 49mpg and the worst 36mpg, but the trip computer always shows better figures.

1.5 TSI MPG.jpg
That’s interesting that as I’ve got a 16 plate Kadjar 1.5 D and was getting a good 48 around town and about 63 on motorway journeys, it’s been for it’s mot and service and was told it had a recall for the onboard computer and infotainment system, now the fuel economy has gone way down to 36 around town and 55 on motorway I’ve rang them to find out why it’s suddenly dropped that much.
Hi fez74uk.

WLTP doesn't in itself change a car's actual fuel consumption, it merely makes the numbers used by manufacturers more realistic of everyday driving.

That said, changes to emissions regulations mean that manufacturers will constantly be driven to reduce CO2 and NOx emissions, which is accomplished through lower fuel consumption and more efficient combustion, plus other measures like catalytic converters and exhaust gas recirculation. However, it is generally the case that new emissions regulations are not retrospective due to the amount of work and money that would be needed to make older cars compliant, if even possible.

What may have happend with your Kadjar is that Renault may have issued new software which your dealer applied to your car, either for the trip computer or the engine management computer or both. It is unlikely that a change to the ECU would produce such a marked change to the mpg without also displaying other effects, such as loss of power, but Renault may have decided to bring the mpg reported by the trip computer into line with the WLTP figures.

Of course, the above is assuming that the drop in your mpg is just a change to what is being reported by the trip computer and the actual consumption is still the same. To be sure, you would need to fill the tank to the top and note the mileage reading then when you have used half a tank or more, fill it up to the top again and note how much fuel you added and the new mileage.

The mpg is the distance driven between fill-ups divided by the number of litres used then multiply the result by 4.56 (the number of litres in an imperial gallon). Of course, you would also need this figure from before the service and update were applied.

I hope that helps your understanding.
1.5 TSI DSG R-Line Indium Grey, rear view camera, park assist.
Ordered 22/06/18
Built w/c 25/03/19 :(
With dealer 13/05/19 :P
Collected 20/05/19 :D

Barnaclebob
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Re: Fuel economy..

Post by Barnaclebob » Tue Apr 02, 2019 11:11 am

Impala, your very comprehensive description on the this subject appears to very accurate and informative - for some people, but in truth, for most people it goes far too deep.
I imagine that most people (my self included) are happy enough to go along with the vehicle’s inbuilt consumption monitor - both Voyage and Long Term.
Whether the vehicle’s calculations are “truly accurate” or not is not so important because any inaccuracy is constant and therefore figures shown are comparable amongst owners. My own “Long Term” consumption is currently 38.6 mpg and my driving can be described as “spritely” - I don’t hang about. Whereas my wife, when she goes on long trips she gets a much better consumption and will get that figure way up into the 40’s - but then she’s like a mobile chicane on the motorway, and keeps the air conditioning off! When I’m driving she’ll switch it on and brag she gets a better mileage than me...!
Regarding your “tank full” calculations, is that filling to “first click/cut out” or is it to the “brim” using No.1 eyeball? There can be a big difference in volume(s) over the long term. Then, you use the conversion factor of 4.56 for litres in an imperial gallon? If we’re being pedantic, then this is not accurate. The correct figure is actually 4.54 (more accurately: 4.54609). Again, not so important but in the long term.... So, your method is fine for your own records as your figures are constant to you. But these can not be truly compared to others...? Unless you define your method...
Now, if we all use the same inbuilt vehicle consumptions we can actually compare our individual results - and that I think most people want to do?
Personally, I chose the 1.5 tsi dsg because I’m not so concerned about consumption (but I am interested) - otherwise I’d have chosen the 1.0 tsi. I enjoy my motoring. The 2.0 tsi was too much...
T-Roc, SEL, 1.5 TSI, DSG, Indium Grey Metallic,
Winter Pack, Electric Tailgate.
Ordered 04-Mar-2019.
Bought 20-Mar-2019.

Impala
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Re: Fuel economy..

Post by Impala » Tue Apr 02, 2019 2:54 pm

Thanks for your comments Barnaclebob.

The 4.56 was a typo due to my keyboard sometimes missing keystrokes.

You are quite right about everyone to his own, and for me I fill the tank to the top using the eyeball technique as you can often get early pump cut-off due to frothing with some brands of petrol.

However, my comments were meant to be about possible different factors at play rather than a discussion abot the absolute mpg figures.

The main reason I went into so much detail ws an attempt to account for the marked change in fez74uk's Kadjar mpg, and the difference between Potsy's Golf and T-Roc. Reliance on the trip computer would otherwise suggest that fez74uk's Kadjar had suddenly developed a petrol leak or some engine problem, and tht Potsy's Golf gave much better mpg than a T-Roc. Hopefully, my comments have given them some re-assurance.

I think it is accepted that trip computers, in the past, and manufacturers claims wre ambitious in the mpg figures they gave and I have speculated that manufacturers have made some changes, perhaps as a result of WLTP, and the figures are now more accurate. The proof of the pudding will be comparing the trip computer with my own calculations after I get my car.

In terms of assessing whether or not a T-Roc gives a good mpg in comparison with other cars, a standard method which produces accurate measurements and works across brands with consistency and is unaffected by the vagaries of different trip computers, is IMHO the best. Isn't that what WLTP is all about ?

The trip computer, as you say, is perfectly adequate for comparing one journey to another (or one driver to another) for the same vehicle and I often use the instantaneous consumption to adjust my driving style when trying to get from A to B if low on fuel.

But everyone to his own ... I'm not suggesting anyone need to use the same method as me and whatever works for you and you are happy with is fine :D

ps. I haven't corrected any typos in the above :D
1.5 TSI DSG R-Line Indium Grey, rear view camera, park assist.
Ordered 22/06/18
Built w/c 25/03/19 :(
With dealer 13/05/19 :P
Collected 20/05/19 :D

Potsy
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Re: Fuel economy..

Post by Potsy » Tue Apr 02, 2019 5:45 pm

Thanks Impala, I will fill it up and use your method to calculate an accurate figure.

I think my driving style in the manual golf was very much biased towards economy, whereas so far I've been a little more 'Lead footed' in the T Roc.

All that extra power and the quick and smooth gear changes have gone to my head ;)

Will see if it gets better as my usual frugality kicks in over the coming months.
T Roc SE
1.5 TSI DSG
Black.

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