Petrol consumption problem - average Fiesta MPG?

jimdriver2 · 14 February 2008 at 2:32PM

Well i've been using MSE for ages now, though up till now never posted on the forums. But i've got a bit of a car problem, so i'm hoping this will be a good place to ask a question and get a little bit of advice.

I just bought a W Reg Fiesta from a garage. It had 72000 miles on it, and is a 1.3 petrol engine. It's got a full service history, and is in very nice condition.

However its giving me, what seems to me anyway, to be pretty bad MPG performance. I've had a Fiesta previously, and that used to give me about 36 MPG doing city driving, and about 40 MPG on the motorway. My new Fiesta however is only giving me about 24 MPG in the city, so I took it for a drive on the motorway and it only gave me 34 MPG. Both of which seem far to low to me.

The garage I bought it from said they'd fix any problems that a diagnostic showed, but the guy I spoke to seemed to think those were reasonable MPG performances. Although they did advertise it as doing 40 MPG.

Does that sort of performance seem to low, or am I expecting to much from it?

thanks in advance for any help.

Wig · 14 February 2008 at 3:03PM

The data says it should get
32.5 Urban
48.7 Extra Urban
40.9 Combined

How are you measuring it? What speed was that on the motorway and distance?

It's always going to be a bit innaccurate doing self tests especially if the distance is short. IMHO you have to fill it up at the pump until it clicks fill it a bit more slowly, till another click, then more.... until the thing clicks off all the time.

Do a long distance motorway at 56mph atleast 100 miles and the more the better, better to do 300 miles. Then come back to the same pump and repeat the filling process.

I think what you got is too low - providing you were not doing 70 - 80 on the motorway. I think as they advertised it as returning 40mpg you can hold them to that, have you still got the advert? How long since you bought it?

What I would do is test the mpg again as described above.
Let them look at it. If no joy then take it to another garage and ask them to try to identify why mpg is not what it should be.

Did it come with a new MOT? Did you get the emissions data sheet? Might be worth having the emissions checked independantly.
High fuel use would I think cause HC to fail.

Maybe ask for a compression check, but you can do this yourself with a gunson's from Halfords if you feel like it. It requires the ability to change a spark plug.

balsingh · 14 February 2008 at 3:46PM

24mpg around town is pretty poor for a 1.3 Fiesta. I used to get more than that round town when I had a BMW 325i. One thing that comes to mind is that the engine may be running too cold. Get the thermostat checked.

Cardelia · 14 February 2008 at 3:47PM

The 1.3i engine just isn't very good. I had a V-reg Fiesta with that engine and struggled to get it up to 40 mpg on motorways even when it was new. The 1.3 engine was based on the 80s technology which went into the MkII (I think) Fiesta - it was updated a bit since then, but it's not nearly as economical (or powerful) as the 1.25 Zetec which replaced it. Your mpg figures are a little lower than mine, but only by 2-3 mpg.

You'll definitely need to keep an eye on the oil though. When I got rid of mine, I was getting through about a litre of oil a month. I asked a couple of mechanic friends and they said it was normal for that age/style of Fiesta (7-8 years) so be careful.

Wig: For my car, I found that I got the best economy at about 75 mph on the speedo. Ford claim the engine runs at optimal economy at 70 mph in 5th gear, so allowing for speed overestimation that seemed about right to me. Oh yes, and the tank only held about 35 litres of petrol so unless you were super-economical with the gas, getting over 300 miles per tank was a rarity!

Keith · 14 February 2008 at 4:01PM

Our Ka has the old 1.3 engine and returns 36mpg combined.

This was worked out for a tank of fuel used last week, with a combination of motorway, country lanes and plodding to work use.

Not sure if your using an onboard computer to measure the mpg? I don't know if the Fiesta has one.

Wig · 14 February 2008 at 4:35PM

Cardelia wrote: »

Wig: For my car, I found that I got the best economy at about 75 mph on the speedo. Ford claim the engine runs at optimal economy at 70 mph in 5th gear, so allowing for speed overestimation that seemed about right to me. Oh yes, and the tank only held about 35 litres of petrol so unless you were super-economical with the gas, getting over 300 miles per tank was a rarity!

Wow that's a small tank, I couldn't live with a car incapable of doing 300 miles before a fill up. But the book would have you believe that this car is capable of 370miles @ 48mpg on the motorway however the fuel light would presumably come on around 300 miles.

In light of what you say about tank size 200 miles would have to do.

jimdriver2 · 14 February 2008 at 5:39PM

thanks for all the replies guys. It does sound like there is something a bit problematic with my car.

I'm only doing short distances in it, as I had to move house and got a place much closer to work, but still need to drive in as I have to use the car for work. I was hoping for about 30 MPG under those conditions.

Ironically I only bought the car because my previous car had fuel problems. My garage tried replacing the air flow sensor, temperature sensor and something else and that only improved it slightly. They reckoned then it was the ECU, which costing around £400 meant it was sensible to just buy a new car.

The garage I bought the car from had listed 40 MPG in the window on the sort of stat sheet, so if it doesn't even do that on the motorway I reckon I have a case for getting them to fix it

Petrol consumption problem - average Fiesta MPG?

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