Hi im new to the group I have a fiesta st line 125bhp it's a 2019 I have had the car a year and ever since I bought it the acceleration is very poor I thought it was supposed to be like that and the fuel goes down very quick getting worse as I went shopping today 3 mile round trip and fuel display went from 305 miles down to 255 miles has anyone else had the same problem 

Hello Paul,welcome to the Ford Owners Club.

Repost your question in the FIESTA forum and you will get some answers

7 hours ago, Paul alton said:

the fuel goes down very quick getting worse as I went shopping today 3 mile round trip and fuel display went from 305 miles down to 255 miles has anyone else had the same problem 

You need to calculate your MPG. Don't rely on the trip computer as its not very accurate (as you've discovered here).

First step is brim the tank, reset the trip computer, drive until you need to fuel up again. Record the miles driven since last fuel up, and the litres of fuel you've put in. You can then work out your MPG.

Hi Paul, yes, as @unofixsuggests, best posted in the Fiesta forum.

I agree with Luke on the fuel calculation - you really need an accurate figure to draw any conclusions on mpg.

We don't know what you've been driving before so it's not that clear what you mean by "the acceleration is poor" and what you may be using as a yardstick.

You say you've had the car for a year - has it always performed poorly? Presumably it's still under warranty so have you raised the issues with your dealer/Ford?

Other thought is, are you using Eco mode? Only tried it a few times but on my car that dramatically reduces performance.

Since the issue of the fuel computer seems to be a source of concern/confusion to many let me try and explain.

So when you last put fuel in the car the computer looks at how the car has been driven in the last X miles and what sort of MPG the car HAD been getting in those last X miles. Based on that information the fuel computer looks at how much fuel is now in the tank and calculates that if everything remains as it has been then you will have a range of Y (for your car 305 miles).

However (there is always a 'however'), when you set off on your next trip things are not the same as before, many little things will probably be different. For example the weather may be colder, you might have the heater on higher. Maybe you need to use the headlights, and possibly the wipers. Coupled with those kind of changes there will also be road conditions and driving style. So previously the car may have been driven on main roads without much stopping and starting. Your acceleration was fairly constant and quite easy going, hence the fuel computers figure of possible range Y  miles.

What happens when on your next journey the cars actual MPG reduces due to various changes as I've outlined above. So now the computer looks at the new data and realises that due to the increased use of fuel the original calculation of Y miles is now wrong. The computer takes the new figures and recalculates the expected range if things continue as they are now. It concludes that with the use of fuel at the current MPG,  that you now have a reduced possible range and comes up with a new "Distance to Empty" of only Z (for your car 255 miles).

Next time you use the car it might be on an easy drive on a long straight main road and little traffic and so you start the journey with an estimated range of Z miles, but things have improved and your actual MPG has improved and so as you're driving the fuel computer recalculates and your range increases from the estimated Z to lets say Z+ despite the fact you have driven a few miles.

In short the "Distance to Empty" or Range is purely and estimate based on previous MPG and journey conditions. It is flexible and is constantly adjusted both up and down as the fuel computer takes its best guess at how far it thinks you can go.

Long answer but I hope it helps.