MPG reading completely wrong

hi folks, does anywhere know the fuel consumption is read from? is it the injector pump?

ive got a problem, my 2.5 rangie seems to be using a lot of fuel and also my mpg reading says im doing anything from 40-60mpg, which is of course totally wrong. i put 40 poundsworth of diesel in today and im going to see how many miles i do on it, what sort of miles of mixed driving should i expect to achieve?

Low to mid twenties I would reckon

this is the first time ive set the mileometer to check but i think im going to be lucky to get 100 miles to this 40 pounds.

joshydee said:

this is the first time ive set the mileometer to check but i think im going to be lucky to get 100 miles to this 40 pounds.

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I can do a lot better than that in my V8 !

ill have to see, although especially at night its noticeable the amount of what looks like vapour you can see in the headlights of the cars behind.

I get a mix of 23mpg from my 2.5dse automatic, 20 mpg around town and about 25mpg driving sensibly on the motorway.

I get 26mpg mixed driving and 29 on a long run from mine, pushing it along I'm down to 23 driving like an old fart and I can get 31/32.
I think it picks up the mpg from the throttle position sensor and the speedo for distance. I don't think it gets a feed from the injection as fitting a tuning box fools the mpg readout into thinking you are doing more mpg than you are presumably because you are using less throttle to get the same amount of fuel for cruising along. I checked my average at 26 by filling up and doing the maths when I next filled up, my dash thinks that average is 29.8.
That £40 would do me for best part of 200 miles.

i got 160 miles to the last 40 quid, i work it out at about 24mpg...