MPG And Range Not Matching

[T50 GSW]

Right, I was wondering if anyone can shed some light on this problem for me.

I picked up a 59 plate Zetec S TDCI about a week ago. I've been driving around in it everyday since and the MPG says I'm averaging around 58 (I reset it when I picked it up from the dealers). The MPG is a combined cycle and if the car acheived this I would be chuffed. I don't drive with a massively heavy foot but I try not to thrash it because that completely defeats the object of buying a diesel for the mileage.

The problem I'm having with it is that the range on the trip computer says that I'll be out of fuel after about 455 miles. With a fuel tank of roughly 9.5 gallons (if I'm not mistaken) I should be getting about 550ish miles per tank.

Does anyone know if there is a reason for this? I've seen listings on other sites and stuff saying people had problems with this and kicked up a fuss with Ford and had their ECU reflashed with newer software which seemed to correct the misalignment. I don't know if this might be a fault with mine, I'm considering talking to the dealer I bought it from and trying to get the ECU done, but I don't want to cause issues if there's something different causing the problem.

Thanks guys

[Blueoval09]

The best thing to do is ignore the trip meter and do it the old fashioned way. My trip (58 plate 1.6 tdci titanium) was saying 51.6 but i done the calculations and discovered i was actually getting about 61 mpg combined. There's a few free apps about that'll do all the calculations for you if you have an iphone, not sure if theres any android ones though.

[tireboy]

why dont you try checking the margin. you might have the bladder problem which created imbalance on individual tanks. when the bladder falls my computed values beat the screen MPG, whereas in the spring the bladder expands and now it takes a little more gas on each fillup. But overall it averages out pretty close.If you want to do manual mileage calculation, the only way to do them accurately is over a large number of tanks. The tank to tank error will average out over a large number of fuel tanks

[Lord Miff]

It's an 8 gallon tank (40 litres).
and to work out your MPG you don't need an app. You need a calculator.

Miles / litres x 4.546 = MPG