Accuracy of MPG readout

missionary · 17-07-2008

2 tanks since I bought mine. Last tank brim to brim was 49.3 mpg over 50 plus litres of use. Its a 2002 110 elx @ 84000 miles.

But I am going for 52 if I can ! So injector clean and calibrate is next on the maintenance list.

cheers
mish

TinyUK · 20-07-2008

Originally Posted by TinyUK

Ive been reading this thread with interest, my 2002 110 (new to me on sunday) is giving horrendous readings of between 27 round town to 36 on a short run (60 on an A road but only about 5 miles).
My driving style will probably not get me any endurance records as far as MPG goes, but wont get me any points either! Mostly urban mileage and a fairly "average joe" driving style.
Ive only done 30miles or so in it so far and i realise I havent really done enough to get a fair view of the cars consumption plus there will have been a few cold starts over that period.

Ive just filled it up so I will be checking the consumtion by the tank to make comparisons with the computer.

I have a couple of questions-

Firstly, how is the MPG calculated? Is it an average of the previous 5 miles consumption or so (like my old SAAB), or is a much shorter distance or for that matter instantaneous?

And secondly, Is there any particular fault that would increase fuel consumption that I should be checking for?

The cars got 47/48k FSH tyre pressures good, but the car is admittedly due a service. The air filter is however very clean on face value and the car is running very well, no smoke etc.

Well after a couple of thousand miles I know realise that the MPG is calculated from the last trip meter reset, handy having a trip A and B. Unfortunately i'm only getting low to mid thirties in town and low forties on a decent run. I guess that has a lot to do with my driving style and the amount of weight I carried on the only long run ive been on (6up plus luggage).

larkim · 1 Week Ago

Does anyone know if Fiat have been "officially" written to about this cockup? You'd have thought that it was in their interest to have the consumption readout "accurate" (I'd have expected it to under-estimate consumption, if anything at all).

As an aside, I've just got a brand new 1.9 Multijet. Only done 2,500 miles so far, but I'm getting only just over 40mpg brim to brim (read out says about 33.5 - 34). I'm not too impressed with that. Neither myself or the wife are particularly heavy footed with the Multi, and at least 600 of those miles have been nice long runs on the motorway at a normal cruising speed. I don't cruise at 60-65 mph, though; I've not owned a diesel before, so is that a more "recommended" speed for fuel efficiency? The brochure (for what its worth) shows 34.4 to 50.4 as the "range" of MPG, so I suppose I am within that.

Matt

missionary · 1 Week Ago

Larkim wrote...
Only done 2,500 miles so far, but I'm getting only just over 40mpg brim to brim (read out says about 33.5 - 34). I'm not too impressed with that. SNIP

But its a new car - all the cars I have had since 1966 have never given good mpg until well run in. The engine and transmission have to be nice and loose before you can expect a good return.

As for the computer's calculation in USG, I am not really bothered as a brim to brim calculation is always going to be better than any electronic figure. At times we have to be a bit old fashioned ! Don't fret, it will come in time.

cheers
mish

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