Hello all, 

I have a 67 plate(2017) All New Fiesta Zetec 1.0 100Ps, automatic. 

Since owning the car in October I have clocked up 3,000 miles. I use the car to drive to work 5days a week on motorways and A roads, between 30-60 miles a day of speeds between 0-70mph , with a small amount of short distance driving at weekends. 

My computer system is reading that I am getting 33.6mpg. Which I believe to be very bad for the type of driving I do.  I today took it to Ford Services for a booked appointment with a mechanic. With me in the car he reset the computer and took me on a 10-15 short drive with speeds no more than 50mph. The computer now reads 30mpg. He said this is about right for the type of car that I own and no further tests were completed. 

End of story?

I was willing to leave my car for further diagnostics and testing. He was a very nice mechanic but am I to simply take his word of a short drive? I was getting better mpg with my old 1.6ltr focus!

Any advice is welcomed. 

If this is the ecoboost engine, you aren't driving like a maniac, and your tyre pressures are all correct then I would say this value is around 30-40% from what it should be!!

How is the performance of the vehicle? Does it feel sluggish or slower than it should? If so, then it could be a faulty (broken or not calibrated) MAF sensor. 

If you have a personal OBD2 reader then I would suggest plugging it in and trying to see if there is a misfire or fault etc... 

Yes this is the 1.0 Eco Boost. Certainly not driving like a maniac, tyre pressures are correct.

In response to your performance question: It feels great! But I’ve gone from an old Ford Focus which felt like a tank. 

I don’t have any OBD2 reader nor would know how to use one, plus this is a brand new vechine under waranrty, which is why I seeked professional advice. Should I question the advice given and demand further tests?

46 minutes ago, 3750 said:

Yes this is the 1.0 Eco Boost. Certainly not driving like a maniac, tyre pressures are correct.

In response to your performance question: It feels great! But I’ve gone from an old Ford Focus which felt like a tank. 

I don’t have any OBD2 reader nor would know how to use one, plus this is a brand new vechine under waranrty, which is why I seeked professional advice. Should I question the advice given and demand further tests?

Thought so, don't worry I was just checking! 

In that case, I would definitely question what the mechanic said. He may be nice, however something is clearly wrong. If you look at the Fiesta brochure it shows that the combined MPG is over double what you have been achieving (I know they can be a bit unrealistic, but not to that extent).

I thought I'd share my experience, I've got a 66 plate manual Ecoboost 125. I think the official fuel consumption figures are about the same as those in that table above. In my experience, driving with the lightest of touches, in favourable conditions, even a 50MPG average is completely unattainable. When I bought this car I did so in the hope that an actual 40MPG would be achievable. That way, coming from my tired old V6 Mondeo that, at a push, would do 20MPG, the Fiesta would practically pay for itself in fuel savings...

As it is, my Fiesta's computer is currently saying 43.4MPG average but that has been gradually creeping down (from 45.9MPG) since the weather turned colder (probably end of November). A couple of things I would highlight - the best way to get a true MPG is to brim the tank from time to time and keep a record of all your petrol station visits in between and distances travelled in an app like Fuelio. The app will then tell you precisely what your average MPG is. At the moment, mine is 39MPG but before winter it was typically about 42MPG on the app. The other thing I've found is that short journeys involving a cold start really hammer the average MPG. My total commute is 50 miles a day with a mixture of roads (including ten miles of 50mph dual carriageway with average speed cameras on it (meaning enforced economical driving!)), and traffic, and I do give it the beans where circumstances eventually allow. However, at weekend I usually do about six local journeys totalling less than 20 miles where the car hardly gets warm at all. I find that those journeys seriously affect the average MPG. Even moreso now the weather is cold. If your 15 minute journey with your mechanic involved a cold start then I'm surprised you managed to get 30MPG average for that journey, especially as yours is an auto.

How many miles do you get to a tank?

I would brim the tank with fuel (and reset the trip counter), drive until you need to fill up again, then brim the tank full again. Make a note of how much fuel you fill up with in litres and how many miles. Use a website such as this: http://www.mpg-calculator.co.uk/ and work out your real world MPG not the computer estimated amount.

Working mine out on my Focus the computer has been as much as 4-5mpg lower than the calculated amount, i'm just wondering if it's a calculation error on behalf of your car, or whether you are using all that fuel (making it less economical than my 1.6L Focus....)

Don't rely on the dash display for MPG.  Work it out properly.  If its still not looking right then the dealer needs to do a few miles with a fuel flow meter in then fuel line.

Don't even bother using manufacturers Euro figures.  They all manipulate the tests, and do so in different ways, so they're a useless guide to expected consumption and aren't even much use as a comparison between brands.

Thank you for all of these replies. 

I’m going to make a log myself firstly before I go back to them. I’ll do two recordings after two full tanks of petrol and will report back. (: