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Old 7th October 2019, 17:58   #11
SD1too
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Dave,

It's clear from your useful posts that there are far too many variables involved to draw a reliable conclusion. The only way that you're going to judge your fuel consumption accurately is by abandoning the on-board display and the Fuelly software and replacing those with a brim-to-brim manual calculation over a full tank. I suggest that you do this when your wife begins her motorway & dual carriageway journey to work and report back with the result. That is the only way that you're going to get a figure which you can trust.

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Old 7th October 2019, 19:54   #12
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Quote:
Originally Posted by Bernard Fishtrousers View Post
The fuelly.com graph tracks just 454 miles and gives an average of 22mpg - it's two brimmed full tanks - the car had three quarters of a tank when I bought it, I couldn't monitor my first fill up as I sent away the IPK? screen to have the lines removed and it reset the trip meter on the dash when it was re-installed.

I haven't reset the trip computer, but it zeroed itself either when the battery was disconnected whilst the timing belts were replaced, or when the head unit was removed & replaced. I suspect the former.

The trip computer, this evening shows;
Trip 2* - 622.6
Range - 521
Average - 33.6 mpg
& Ave speed - 26.2

The distances are far too small for anything meaningful yet, but the disparity is huge.

*I have no idea how to switch between trip 1 (assuming there is one) & trip 2.
Move your eyes down

Trip 1 is the lower display
Trip 2 is the upper display (I wondered about this for a while too)

I do not know what fuelly is or does (I can guess), I prefer to use the brim to brim, and as long as I get a consistent mileage from each fill, I am happy (that is my choice though ), but I imagine providing you enter the details correctly to fuelly, it will be accurate.

However from what you mentioned previously you expected a drop due the moving around the yard whilst it had work done (that would be a lot of moving though), I am suspecting the IPK was sent away during this time. Perhaps now that it has been reset (it would be by the battery off or being unplugged) that the car is being driven relatively normally. If that was the case this could explain the massive disparity.

I would suggest resetting the fuelly if this is possible, to start afresh. Reset the display too, at the same time, and start from scratch. As well as this, recalibrating the 'fuel correction' would be a good idea, as T-Cut mentions previously (LINK)
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Old 17th October 2019, 18:03   #13
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The 75 has been put into regular service with the fair wife and the first set of results are in;
(I always brim the tank) so; 49.10 litres / 4.54 = 10.8 Galleons!
286 miles / 10.8 = 26.5 mpg - Fuelly says exactly the same.
Just a bit worse than the 2.5 litre manual, four pot 944 which incidentally pulls a frantic 3,400 rpm@70 mph.

The trip computer is still away with the fairies, so with that, the outdated sat-nav & the defunct telly, I've managed to find the off switch.
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Old 17th October 2019, 18:42   #14
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Hi Dave,

Thank you for the first set of data. As a fellow owner of a 2.5 litre automatic I'd say that an average of 26.5 mpg for ....
Quote:
Originally Posted by Bernard Fishtrousers View Post
... a daily 26 mile commute over 4 junctions of motorway with dual carriageway at both ends ...
is terrible.

We therefore have to consider your wife's driving style and the service history of the car.
Quote:
Originally Posted by Bernard Fishtrousers View Post
The trip computer is still away with the fairies ...
Can you translate that remark into mpg please Dave? Can you also confirm that the display was zeroed at the same time as brimming the tank and left alone for the entire 286 miles covered? Thank you.

Simon
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Old 18th October 2019, 19:26   #15
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My next will be better, I've got a hunna mile round trip up to a nano meet tomorrow, but let's see the maths for your last tankful, then.
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Old 19th October 2019, 14:32   #16
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211 miles - 32.01 litres = 7.05 galleons = 30mpg = a PB.
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Old 21st October 2019, 00:25   #17
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I find the Trip Computer on my ZT190 is also about 10% optimistic compared to calculating consumption over several tanks.
The manual ZTs mileage is about 25% better than my previous V6 Freelander auto though. That was an unexpected surprise!
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