Why Is My Fuel Efficiency Getting Worse?

[mikester]

remember the days when i was getting 75mpg average over a tank, once i peaked at 80 something average over a tank. (worked out with maths not the trip computer)??

well now i don't even get close, but get this my commute involves less traffic and more mpg friendly roads, i don't get it. I thought engines get better over time. Mine's gone the other way.

i can't touch 65mpg average anymore. currently on 61mpg over a half tank.

i've been thinking about what has changed other than my journey, i've had two services in between, maybe these have been detrimental. nath, adam, other derv owners, hows your economy holding up or anyone getting the same?

[Magenta]

Ahhh.. those were heady days when I easily used to get 60mpg + from my Fiesta 1.6 TDCI, even though I made very short trips. So your 70 - 80 on longer journeys makes sense to me.

Now, this probably isn't relevant to your question but I now have a 1.4 petrol auto doing the same short journeys - probably the worst possible combination you can have, mpg wise, struggling to get 37 mpg. Significantly though, the figure steadily got worse dropping to 32mpg this year so I talked to the Ford dealer who said that it was possible that the injectors were becoming clogged and recommended a two-stage cleaning additive, one in the fuel and then one in the oil at the next service. I had the fuel one done at a cost of £12.50 and it seems to have worked ! MPG is back up to nearly 40.

Perhaps there is a similar treatment available for diesels ?

[Froggy72]

Have you started using sainsburys diesel as I used that before and I lost 10 mpg. Had a friend who always used it and his car stopped working and they found the fuel tank was full of water. I recomend forte diesel injector cleaner, it worked wonders on my previous diesel car. It costs a tenner, halfrauds don't sell it but have a look on eBay.

[iNath]

You can see my mpg here or by clicking it in my sig.

Got my best ever tank last month of 66.1mpg :D Rarely dips below 60mpg now.

I wonder if your dealer updated the PCM when it was in for a service?

[Jwsturner]

I have a 2009 1.6tdci 90hp titanium and only get 400 miles on a tank which works out at about 50mpg. I drive 80 miles per day and about 80% is motorway and I use the cruise control at 65mph.

I had a 200bhp Mini JCW before this and at 65mph I could get 40mpg on the same route.

My gf has a 177bhp BMW 320d and can get 50mpg out of hers!

My car is due a service and I'm going to see if there are any ecu updates to resolve this. If not then its going to be traded for a 3 series.

So getting 60mpg+ is good in my view

[sambooka]

I have a 2009 1.6tdci 90hp titanium and only get 400 miles on a tank which works out at about 50mpg. I drive 80 miles per day and about 80% is motorway and I use the cruise control at 65mph.

I had a 200bhp Mini JCW before this and at 65mph I could get 40mpg on the same route.

My gf has a 177bhp BMW 320d and can get 50mpg out of hers!

My car is due a service and I'm going to see if there are any ecu updates to resolve this. If not then its going to be traded for a 3 series.

So getting 60mpg+ is good in my view

I know the feeling mate I only get 50mpg out of my 2011 zs tdci 95hp although I do 70 on motorways with cruise control on

[Maleforce]

Hi everyone, I just got back from a 5 week driving holiday through France and Spain, my MPG varied from at worst 51 driving at 75-80 on the motorway to 71 MPG driving at 60 from Madrid to San Sebastian in Spain. I think the following things make some difference other than speed!

a) wet/dry roads, there is more drag in the wet and its been a very wet year in the UK, and also in the wet there is alot more variance in speed.

b ) The Diesel, using the higher octane for me adds 1.5 to 2 MPG and more on a smooth low speed run.

So maybe cos its been really wet this year has brought averages down.

[Jon Bates]

I suffered the same problem with my 1.6 petrol Titanium Focus. After having it serviced I dropped from average 43 to about 37 doing the same kind of driving. They did a PCM update, would this have affected it? Would I have actualyl lost MPG or does it just do the calculations differently? Cheers.

[sambooka]

Hi everyone, I just got back from a 5 week driving holiday through France and Spain, my MPG varied from at worst 51 driving at 75-80 on the motorway to 71 MPG driving at 60 from Madrid to San Sebastian in Spain. I think the following things make some difference other than speed!

a) wet/dry roads, there is more drag in the wet and its been a very wet year in the UK, and also in the wet there is alot more variance in speed.

b ) The Diesel, using the higher octane for me adds 1.5 to 2 MPG and more on a smooth low speed run.

So maybe cos its been really wet this year has brought averages down.

Another thing that seems to make mpg worse is supermarket fuel have filled my deisel zs up at tesco since I bought it 7months ago and never got above 51mpg as a sufferer of lead foot sindrome I expected less anyway the past month I started filling up at bp and it gone up to 54mpg I drive just the same it's still raining the same as it was a month ago and I haven't serviced it

[mikester]

Not buying into this supermarket fuel excuse, I've filled up at the same station for all my years of driving, I've occasionally used Shell and BP but the small increase in economy did not make up for the £4-7 more per tank it'd cost to fill.

So now I find myself asking the same question again as I seem to have even worse consumption than when I first posted this thread. I haven't had a computer update since I got the car in 2010 and for a year and a half after that I was getting magical results, 75mpg average over the tank for example (worked out with maths not the trip).

I'm even considering taking my car to a dealer just for a reflash to latest software to see if it helps but I know they'll charge me an hours labour and it might be worse.

Currently struggling to get over 55mpg over the tank. It's good, but not by my records.

[Sliveredge]

The Temp has a big effect on the MPG i have found mine drops by about 10 MPG in the winter even more if doing shorter trips.

I used to see anything over 55 MPG as an average now this week it has just been over 43.

[b1g_dav3]

I'm on 52 on average per tank currently, think some is the weather. The rest is because I keep giving it some >.<

Ford will tell you 50+ is normal probably. Best thing to do is give the car a service and see what happens if you haven't already.

[sambooka]

Strangely mines doing better mpg now it needs a service than when everything was fresh did 47-49 after service now it needs a service 52 sometimes more although I suppose it could be down to the extra 12500 miles I've done

[TDCiST]

I always see worse Fuel consumption in winter, Running the car to defrost, using more electric items, etc etc etc...