I've just bought an almost 3 year old, Fiesta Titanium X with the 1L EcoBoost (125BHP variety) engine, and I'm a little confused by the dash telling me how many miles I have until I need to fill up and therefore the fuel efficiency.

Before hitting the road I filled the tank to the brim and it told me there was only 247 miles of fuel available until I next had to refill. I then drove around 120 miles home, on the motorway, cruising at 70mph most of the way and the miles to empty figure kept on creeping up until it hit 271 after around 85 miles of the journey. The whole journey used about a quarter of a tank but I'm concerned that the information on the dash is way out and not at all accurate.

The amount of fuel used would indicate I should get almost 500 miles from the tank before having to refuel, yet the computer clearly says I am going to get around half that, and even after driving those 120 miles it still has approximately the same number of miles to empty displayed.

Is this normal?! Is the 500m manual calculation available in the tank about right for this car/model?  Does the computer usually miscalculate so much?

I've come from a 2007 1.4L Diesel Fiesta which would get around 500 miles from the tank also but the miles to empty display on that was always pretty much spot on.

Don't take to much notice of it till you have gone through a couple of tanks of fuel so it adapts to you normal driving style/routine etc. 500 miles is probably possible if driven correctly, we have an ST and managed 430 miles (boring miles mind) although that does have a bigger tank than other fiestas.

But should the computer not already be accurate, given that I had driven the grand total of 2 miles from getting the car to refuelling it, and I checked the miles to empty figure while still on the garage forecourt?

The car also isn't new. It'll be 3 in March and has 12,000m on the clock so surely by not it should know what it can do more accurately?

You're not going to believe this, but here's what I do. . . I ignore that miles til empty until it hits around a quarter of a tank (the petrol light comes on), approx 44 miles remaining on my car, and then I fill it up again. haha

In more detail, that thing is probably accurate if. . . you drive like you're learning to drive. 

2 hours ago, kingdave said:

But should the computer not already be accurate, given that I had driven the grand total of 2 miles from getting the car to refuelling it, and I checked the miles to empty figure while still on the garage forecourt?

The car also isn't new. It'll be 3 in March and has 12,000m on the clock so surely by not it should know what it can do more accurately?

It's trying to give you info on the previous tank of fuel or when the readings were last reset, if the previous driver drove it like they stole it then it's going to base the projected range on that use. Reset all the guages then drive it, see how many miles you get from a tank in the old fashioned way and compare it with the computer after a couple of tanks have been used.

Mine was like that when I first bought it.   After three or four tanks of fuel it had settled down and now is pretty accurate.

Agree with others. It'll sort itself out when you drive it more. My 1.4tdci was on avg 40mpg when I got it but is now on 51.7 and predicts 410miles when full. 

Over summer it was 52.2 and predicting nearer to 440 per tank. Obviously decreased when using hot blowers during the cold weeks not long ago 

So, I'm currently half way through that first tank of petrol having covered 200 miles and the MTE display is also saying 200 miles remaining. If I can get 400m I'll be happy.