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I've commented before on just how accurate the computer seems to be in my car. Well, I've just completed a full year checking the computer mpg v brim-to-brim readings and the average over the year?

30.78 by the computer
30.79 measured brim to brim

I find that quite astonishing.
 

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Thats similar cosumption to me.

The injectors are so accurate that with good software, it should be fairly close.
You're probably right, my 159 is impressively accurate as well, but my previous three cars had similar computer functions, and all three, petrol Golf GTi and Audi and a diesel Saab, weren't very accurate at all. One thing I noticed with all three, though interestingly not with my Alfa, was that they all became inaccurate, hopelessly so with the Audi, as soon as I filled up with fuel in Luxembourg, usually my first fuelling stop on a foreign trip. My A4 had a cruising range of roughly 600 miles, but after filling up at Arlon, the computer read something over 800, and didn't recover from this until Fleet services on the M3 a week or two later.
 

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I've commented before on just how accurate the computer seems to be in my car. Well, I've just completed a full year checking the computer mpg v brim-to-brim readings and the average over the year?

30.78 by the computer
30.79 measured brim to brim

I find that quite astonishing.
You checked EVERY tankfull? You need help mate!:D

Thanks for the confirmation of accuracy.:thumbs:
 

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as soon as I filled up with fuel in Luxembourg, usually my first fuelling stop on a foreign trip. My A4 had a cruising range of roughly 600 miles, but after filling up at Arlon, the computer read something over 800, and didn't recover from this until Fleet services on the M3 a week or two later.
That'll be the effect of filling with a metric gallon.
 

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To explain further, the Golf, Audi and Saab were always optimistic in varying degrees. The fuel consumption of my Alfa is its most disappointing feature, but at least the computer doesn't try to improve on the dismal truth by telling me porkies.
 

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That'll be the effect of filling with a metric gallon.
Very amusing, but I use a factor of 4.55 to convert my litres into mpg. I suppose we can assume that the mileage readouts are reasonably accurate? I work out every single brim to brim mpg figure as well, I'm self-employed and keep all these figures to fend off my accountant and the Inland Revenue.
 

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Oh course I do agree with you, as you may read in a couple of recent posts of mine, one today in the 159 JTD fuel consumption thread and my 1 week and 1000 miles thread. As you will read I am also an ex SAAB 1.9 Tid owner. The computer on that told porkies to an extent that it made me think it was a more economical car than it is.

I do just wonder how many other cars out there 'look' like they are doing great consumption, the owners having their ego massaged by a computer.
 

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I've always assumed the mpg a car's computer shows to be reasonably accurate. It does make me wonder now whether the Vectra cdti I had previously really was averaging 50mpg - I never thought to check it manually! I'm happy to believe now that it was overly optomistic.....makes the 33mpg from the 2.4jtd more bearable!
 

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I've commented before on just how accurate the computer seems to be in my car. Well, I've just completed a full year checking the computer mpg v brim-to-brim readings and the average over the year?

30.78 by the computer
30.79 measured brim to brim

I find that quite astonishing.
I find that astonishing too.

On a day to day basis you must have known quite early on that you were getting "about" 30 mpg.

So why spend so much time over a year with spreadsheets et al finally proving that which you knew already?

I don't get it - time could have been spent doing something - dare I say it, interesting?
 

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I don't get it - time could have been spent doing something - dare I say it, interesting?
Nothing beats hard data. And nothing beats having other people gather it for the rest of us!

Thanks Fraser, I find it interesting anyway, and it puts some of the adverse comparisons with other cars in context.
 

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Nothing beats hard data. And nothing beats having other people gather it for the rest of us!

Thanks Fraser, I find it interesting anyway, and it puts some of the adverse comparisons with other cars in context.
Agree totally. I also concur with what KAYEM says, my previous car was a SAAB, that satisfied my belief that my 1.9 Tid was doing 47mpg. The computer was of course telling porkies, 43mpg was the truth brim to brim, about the same as my Alfa. It seems some manufactures will tell you what you want to hear!
 

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Personally, I don't care WHAT the computer tells me onscreen, all I know is since I bought this 147 JTDm 1:9 ltr, to replace my previous 2:Ltr petrol 147 Lusso model. I am saving a FORTUNE on Fuel, so it can tell me what it wants. I'm HAPPY !!!!!!......:thumbs: :lol:
 

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Discussion Starter #18
I find that astonishing too.

On a day to day basis you must have known quite early on that you were getting "about" 30 mpg.

So why spend so much time over a year with spreadsheets et al finally proving that which you knew already?

I don't get it - time could have been spent doing something - dare I say it, interesting?
Hmm - let's see. 10 minutes to set up the spreadsheet a year ago, 15 secs to write the numbers down when I fill up my tank (once or twice a fortnight) and, say, a minute to input the data to the spreadsheet (once or twice a fortnight). Loads of time to do other things.

Thanks for your opinion Paul. Just think what you could have done with the time you used up to give it:p
 

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Cheers Fraser.

I checked a couple of tank fulls when I first bought the Brera and was happy with read out accuracy so have not bothered since.

Did you find that accuracy was affected when you had the Autodelta box plugged in?
 
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