Mpg.

[mumof4]

I know we have covered this subject till the cows come home but i have a problem.

 

Now i know that my car should average well over 42mpg on a bad day and on a good day if im really good nearly 50.

 

Now last night down the M4 at a steady speed of 70mph...my average was 38.9....that is the highest i can get it.I have tried different speeds,different roads,in town,out of town,anywhere to see.

 

Now the torque is fine..it pulls nicely away...zooms everywhere and i can hit speeds of..ah....better not say... :blink: .......

 

I have checked the MAF ...i have checked things where i didnt know what i was checking..all pipes etcc that i see in the engine bay seem to be going where they are supposed to go..

 

 

So what would cause this loss in mpg????No smoke that i can see coming out the rear...No noises creaks or groans that werent there before....gears change is still quite loud but i cant see that affecting mpg...Now when i reset the mpg.....for about 5 mins the reading flicks between 85 and 176mpg...now whether that is because it is still trying to work out what i am doing i have no idea...but after that it does settle down to around 36/38mpg.

 

Any ideas?

[Tigger]

I would have thought you should get more than this.

 

Even taking air con and wind.

 

Did a trip to Brecon on Sunday MPG 50mpg over 300miles. Stuck at 65-70mph on motorways stop start on single track.

 

Air con working it does knock you down

[mumof4]

Climate control wasnt on....another thing i noticed...when i was using the windows..the main beams would dim a bit..is this normal?

 

 

I know i should get more than this...will check the air filter later on this aft even though it was supposed to have been changed at service.

[Davetheref]

Try changing out of third gear :blink: :D

 

 

Seriously though, my overall average is about 47 mpg in a 130 ps diesel. On my journey to the train every day (17 miles each way) I try to keep to around 55mph. Around town I never really check.

[Andrew T]

The Government fuel figures are best used as a rough guide to comparing different cars than as an indication of what a car will achieve in your hands. By this I mean that if you buy the car with a Gov't combined MPG of 40 compared to one with an MPG of 30 that car should deliver about 33% better fuel Consumption in you hands. In reality the one that should deliver 40MPG may only give you 33MPG, but had you bought the one with a figure of 30 it will only give you 25MPG.

 

Fuel consumption test are performed in a laboratory and cannot account for the effects of wind resistance. The Galaxy must have one of the biggest frontal areas of any car tested. If you were to take the Galaxy and another car with a lower build, but which returned the same Extra Urban fuel figures and cruised them side by side on a Motorway you would surely find the lower built car was actually returning higher figures than the Galaxy.

 

Other factors like tyre pressures, accessories in use, windows open, roof racks fitted, quality of servicing, mileage covered by the engine, hills and head or tail winds and most of all driving style will all have an effect on MPG returned.

 

Lastly do manufactures build cars to produce good test figures rather than to deliver good real world MPG?

 

I've driven a well above average mileage at my own expense for the past 20 years, so I've learned how to drive economically. I get 32MPG overall from a 2.3 Petrol, but only with the gentlest of driving can I match the Gov't Extra Urban figure for the 2.3 of 36.7MPG.

 

To conclude; only use the official figures to choose your car, don't expect to achieve them.

[raymac]

Climate control wasnt on....another thing i noticed...when i was using the windows..the main beams would dim a bit..is this normal?

 

 

I know i should get more than this...will check the air filter later on this aft even though it was supposed to have been changed at service.

 

The windows thing happened to me also so i would imagine that is normal, the bit about the mpg going between 85 and 179 mpg for about 5 mins could be the setting for mpg on setting no:2 as oppossed

to being on setting no:1

 

fully loaded and roofbox (5passengers and luggage in area where 7th seat removed) at average of 75/80mph the higest average i got was about 37mpg this with climate control on at all times , yesterday went to leeds 3 passengers no roofbox climate on average 75/80mph highest mpg just over 43mpg , i don't think aircon/climate makes much difference to overall consumption i have been advised that it increases consumption between 3/5 % so not that bad :blink:

[jkspoff]

I know we have covered this subject till the cows come home but i have a problem.

 

Now i know that my car should average well over 42mpg on a bad day and on a good day if im really good nearly 50.

 

Now last night down the M4 at a steady speed of 70mph...my average was 38.9....that is the highest i can get it.I have tried different speeds,different roads,in town,out of town,anywhere to see.

 

Now the torque is fine..it pulls nicely away...zooms everywhere and i can hit speeds of..ah....better not say... :blink: .......

 

I have checked the MAF ...i have checked things where i didnt know what i was checking..all pipes etcc that i see in the engine bay seem to be going where they are supposed to go..

 

 

So what would cause this loss in mpg????No smoke that i can see coming out the rear...No noises creaks or groans that werent there before....gears change is still quite loud but i cant see that affecting mpg...Now when i reset the mpg.....for about 5 mins the reading flicks between 85 and 176mpg...now whether that is because it is still trying to work out what i am doing i have no idea...but after that it does settle down to around 36/38mpg.

 

Any ideas?

 

My MPG is between 33 and 50mpg, depending on style of driving and type of roads/length of journey. Mine has been remapped and still achieves about the same mpg as before, if not slightly better on a long run. Your electric windows shouldn't really dim the head lights, check the voltage output from your battery, as it may be on its way out.

[jwilliams]

Having the windows open will make your mpg drop as it increases drag.

 

You may be better off with air con on!

[Bigjeeze]

I average 6-800 miles per week and If I were to beleive the on board computer then I am doing around 50mpg - but when I check the mileage by fuel used I am averaging approx 44mpg - which I trhink is very good. I usually stick to the posted speed limits but I do drive almost exclusively on the Cruise control so this removes most of the stop start driving you do when constantly slwoing down or speeding up. I find that the climate control takes around 3-4 mpg off but as I never turn mine off I don't notice this anymore and so this could bring my average up. As has been said ,condition - tyre pressures , windows , Roof boxes etc all play their part. You could if it matters to you, also try removing excess seats to see if lightening the load will assist (I think this is daft).

 

The fluctuating readings can be caused by a number of things - gearchanging - going up hills - going down hills so until they stabilise can't be taken as read - also the readings are average and again you should not beleive them totally. If you have a change from the norm then you have to find out what has changed.

[Masked Marauder]

Well last night I averaged 8.4 MPG in a vehicle that he manufacturer says should return 8.9 MPG. I do get 50+ MPG in my Bammer on a long long motorway run.

 

The only sure way to tell is to brim the tank, do a full tank's woth of mileage and then brim the tank and from there calculate how much fuel you have used.

 

I certainly would not trust the computer to work it out.

[Guest MATT jr]

we all know computers lie - esp cars, as it mesures the air going in the engine and NOT fuel.

 

from a TV program they did a test, and windows OPEN with aircon OFF is better for MPG.

 

if your gears are F%$Ked, then could this be causing excess load on the engine?

 

if everything is how it should be, then its driving style or load.

 

MJR

[Masked Marauder]

Volvo did a test with windows and air con and concluded that the air con option was 5% more fuel efficient. All Volvo heavy trucks now come with climate control as standard for that reason.

 

Also MO4, watch for uneven front tyre wear. Excessive toe, particularly out, can cause a sizable drop in MPG. Look for accelerated wear on the inside or outside edges of your front tyres.

[Steveenduro]

I found that tyre pressures made the biggest difference with mine.

I got 50mpg coming back from Wales on the weekend, with 5 POB + luggage. (+ aircon - Yes it works again!).

Mind you, I did have the good old prevailing westerly to help me along!

 

I tend to use the top book values for tyre pressures (around 45psi I think).

[mumof4]

Ok..i dont have a roof box...was only me in the car....cc was not on....window was open a tadge and i noticed the lights when i closed it....tyre pressure is fine as i checked the other daythe wear on the outer ridges of my front tyres i was told was down to going round roundabouts..was told that by a tyre place that i know and trust..there is nothing sticking out from the car which shouldnt be..there was a quarter of a tank in the car...no loads in the car..just me and the seats,oh and a scooter!!lol

[mumof4]

Right..back on track..the worst it has been was when i got 28.7 mpg doing 70 on a dual caraigway..could a blocked air filter cause all this?..Usually i can get in the mid 30s just going round town...but over the last week or so it has been steadily dropping.Hmmm...

[Andrew T]

A blocked air filter would happen slowly, not suddenly. Unless it's never been changed I think it's unlikely to be the culprit, but it woudn't take five minutes to have a look at it. In terms of the spot readings that you're getting, it could be simply that you were heading into a strong headwind at the time and maybe going slightly uphill . Is it windy where you live today? As MM said, the only way to check your consumption accurately is to do a manual check.

[Bigjeeze]

First things first: When did you first notice this or has it crept up on you?

 

If it is recent, has anything occurred (like hitting trees) that might have an effect??

 

Have you checked your tyre pressures?

 

Are you sure that this is a regular thing or is it just a one off?

 

Air Filter - This could cause a problem - when was it last chnaged - the service interval is around 20K miles or 2 years I think - for a mere

[mumof4]

Ok..air filter was changed at the service 5 July...

 

Tyre pressures are fine..i checked them myself last week..

 

am sure it is a regular thing as i noticed it last week and have been monitoring it since..mpg is going down

 

Yes i hit a tree but the air filter was undamaged and everything was checked out

 

 

I have done..1880 miles since service....(wow!!..just checked!!)....didnt think id done that much..no wonder breaks...naffed!!)

[Bigjeeze]

Ok..air filter was changed at the service 5 July...

 

Tyre pressures are fine..i checked them myself last week..

 

am sure it is a regular thing as i noticed it last week and have been monitoring it since..mpg is going down

 

Yes i hit a tree but the air filter was undamaged and everything was checked out

 

My reason for asking this is you mau have dmaged the geometry - something may be bent...

 

 

I have done..1880 miles since service....(wow!!..just checked!!)....didnt think id done that much..no wonder breaks...naffed!!)

[mumof4]

I trust the guy who fixed my Gal..and i know he went over it with a fine tooth comb..if the geometry was out/bent..he would have fixed it and not left it.

[Scorpiorefugee]

I may as well chuck in my two penn'orth.

 

Has this happened since the service?.......

 

Has anything in particular, apart from the criminal profit making by the oil companies, made this a particular sensitive issue?

 

It's already been suggested that you disregard the fuel computer and work on tank full to tank full.

 

Our 115 Ghia is more thirsty than the old 110 which is the workhorse. I struggle to get much more than 42/43 out of the 115 although I have managed 50 on a couple of occasions.

 

I find that the old 110, without a computer, settles at around 45/46 driving to the speed limits and I know that, from a full tank, I can get 100 miles down to the full mark, 250 down to the 3/4 and 400 - 420 to 1/2 and 550 - 570 down to 1/4.

 

The truth is known when I top it up because I recon to get 10 miles to the litre. So, fill it up, use it for a bit, divide miles by 10 and if that's what it takes to fill it up, I,m happy.

 

I can't suggest any causes because, after years of high mileage, I've only ever found one cause of high fuel consumption - my driving habits.

 

I hope some of this is of use.

 

Ron.

[JONESERIC]

Hi all

 

We have a 1997 1.9tdi with a tunning box fitted since 1998, we have done 150K in this car, the on-board computer normally shows 55 mpg and I have seen 62 mpg as a I drove home after a late shift in serious fuel saving mode. Having had this car since new we have checked its fuel consumption by filling the tank every time and recording miles run. Therefore the data is accurate.

 

I already here howls about how the various chips alter the way the on-board computer measures MPG, but we have over the years seen a real measured gain of approx 5 mpg. The on-board fuel computer is at best a compartive device. What is important is how you drive the car in those all important first few miles.

 

My wife drive our 130bhp Gal to work everyday through a semi rural area and that car records 550 miles per tank with the Sharan recording approx 650 per tank.

 

 

Eric

 

1997 Sh 1.9 Tdi

2004 Gal 130 tdi

[Vanbursta]

I would be REALLY happy if I could get even close to your MPG, 14-20mpg round town, 25-27mpg on a run!!! Luckily I have a friend who follows me everywhere with his tanker :-)

[katman]

Just started using my Fuelcost spreadsheet again.

 

Never used it with the Galaxy before but when I used if for my old PUG 309 GLD I used to get around 54mpg.

 

Only had 4 tankfuls of petrol so far so a bit too soon to accurately work out the true consumption but currently around 22 mpg :D :D

 

Having said that, it is mostly round town driving with the longest runs being 18 miles. Aircon has been on all the time as well. Going away soon so a decent 200+ mile run each way and with the driving around will probably do the between 600 - 800 miles in a week.

 

Will be interesting to see how that affects the figures.

 

Took the kids to the park yesterday and a T reg Alhambra parked up next to my P reg Galaxy.

 

Got chatting to the owner

 

Me... "Petrol or Diesel"

 

Him... "Petrol but I wish I had bought a diesel"

 

Me... "Me too.. what size engine?"

 

Him... " 2 litre"

 

Me... "Same as mine, any idea what your MPG is?"

 

Him... "Only about 20 :D"

 

Me... "Mines about the same... is that with Aircon all the time ?"

 

Him... "Aircon doesnt work"

 

Told him all about the "place to be" so we will see if we get a new Bamma owner with knackered aircon soon.

[NikpV]

Right..back on track..the worst it has been was when i got 28.7 mpg doing 70 on a dual caraigway..could a blocked air filter cause all this?..Usually i can get in the mid 30s just going round town...but over the last week or so it has been steadily dropping.Hmmm...

 

 

declining mpg was the earliest sign that our maf was degrading - I thought you had changed yours recently - was it a new one?