In March 2009 I bought a new 1.4 diesel Match. Since then I have covered 12,000 miles at an average of 45 mpg (against the official figures of 50/63/72). This is very little different to the 1.4 petrol Polo which I previously owned although the official figures for the diesel are 40% better than the petrol ones. My motoring is "rural" with journey lengths usually of 8 to 10 miles with one up.

All my previous cars have attained the average of the urban/combined figures or better. My current 1.4 diesel Polo is by far the worst and the dealer has said that there is nothing wrong with it.

I would be grateful the hear what consumption other owners of 1.4 diesel Polos are getting. The limited information which I have obtained all indicates that I should be getting a fuel consumption of 55 to 60 mpg.

Diesels are poor on fuel on short journeys.

Diesels are poor on fuel on short journeys.

This statement isnt true, I'm having a consistent return of 55-60 mpg with my tdi and thats on short journeys.

One thing to take into consideration is the fuel price in your area, what is your fuel price per litre??

Edited 31 May, 201016 yr by Monkey-man

Diesels are poor on fuel on short journeys.

This statement isnt true, I'm having a consistent return of 55-60 mpg with my tdi and thats on short journeys.

Yes it is.

One thing to take into consideration is the fuel price in your area, what is your fuel price per litre??

Has no reflection on MPG.

Diesels are poor on fuel on short journeys.

This statement isnt true, I'm having a consistent return of 55-60 mpg with my tdi and thats on short journeys.

Yes it is.

Dude it isnt, this isnt the first diesel i have owned and its never been the case that on smaller journeys its terrible on fuel consumption.....least of all deffinately not less efficent than its petrol counterparts, granted just as with petrol engines on shorter journeys fuel efficency does decline, but not to the rate that the gent is saying above.

But i know fuel price doesnt have an effect on mpg...well not directly, but alot of people work out their mpg buy how much fuel they were putting in, ie £10 of fuel at £1.169 (what the fuel price was in the majority of places) 8 or 9 weeks ago would get you just over 2 gallons, now if people are still working out what they think to be their mpg to how much moneys worth of fuel they are putting in then this will have an indirect effect on what they believe to be their mpg, as it will obviously drop, but the fact is there car isnt becoming less efficent, its just your not getting as much juice for your dollar.

Edited 31 May, 201016 yr by Monkey-man

Sounds about right really. Diesels aint that good on short journeys as said above. Diesel engines are most efficent when warmed up, there is no 'ignition' source (spark) in a diesel engine, so below optimum engine temp you don't get complete combustion (i.e. on shorter journeys), so aren't getting the best bang for buck as far as fuel consumption goes. Not saying its worse than a petrol engine by any means, just don't go expecting a 65mpg return on a 5 mile shopping trip.

I get a weekly average of around 50mpg, a lot of which is motorway miles. Motorway cruising, when warmed up, your probably getting 60+ mpg easy, but those initial 5 - 10 miles of normal roads with a 'cold' engine, your probably at around 30mpg max, so your figures sound ok in reality.

Sounds about right really. Diesels aint that good on short journeys as said above. Diesel engines are most efficent when warmed up, there is no 'ignition' source (spark) in a diesel engine, so below optimum engine temp you don't get complete combustion (i.e. on shorter journeys), so aren't getting the best bang for buck as far as fuel consumption goes. Not saying its worse than a petrol engine by any means, just don't go expecting a 65mpg return on a 5 mile shopping trip.

I get a weekly average of around 50mpg, a lot of which is motorway miles. Motorway cruising, when warmed up, your probably getting 60+ mpg easy, but those initial 5 - 10 miles of normal roads with a 'cold' engine, your probably at around 30mpg max, so your figures sound ok in reality.

Thanks for the information. However, the best I have ever returned is 46.5mpg for a 300 mile journey along the A1 keeping to the speed limit

That's pretty shocking then, if I stuck to 70 I could probbaly get 46 mpg in my 16v GTI... I'm sure on that short of run you should be approaching 70 mpg. have you tried a different dealer?

Diesels are poor on fuel on short journeys.

My apologies dude, had a little read and you were in fact right, maybe its just the diesels i have owned then, they tend to be pretty similar in terms of mpg on rural, urban and extra urban driving

Thanks for the information. However, the best I have ever returned is 46.5mpg for a 300 mile journey along the A1 keeping to the speed limit

No worries dude.

Are you going off what a trip computer thing says or actual petrol light to petrol light/brimmed tank to brimmed tank? everyone knows commputers are prone to lying :-D

Check little thigs like tyre pressure, brake rub or even loose body panels, even small things add up to reduce efficiency.

Failing that try cleaning/replacing MAF and MAP sensors, and check turbo is working. Look at air filter condition, make sure its not restricting flow. If the car is thinking its getting enough air but actually isn't it'll still pour fuel in but won't have enough air for efficient combustion = higher fuel consumption for equivalent speed. Does the car smoke at all, especially on start up or on acceleration?

That's pretty shocking then, if I stuck to 70 I could probbaly get 46 mpg in my 16v GTI... I'm sure on that short of run you should be approaching 70 mpg. have you tried a different dealer?

I quite agree. The vehicle has by far the worst fuel consumption when compared to the official figures of all the vehicles I have had over the last 20 years. The average consumption is 15% below the urban figure whereas all the others have acheived at least the average of the urban/combined figures. Infact our other car at present, a Vectra diesel, normally acheives the combined figure and a few more mpgs on a long run.

I will certainly not be using the same VW dealer again.

Thanks for the information. However, the best I have ever returned is 46.5mpg for a 300 mile journey along the A1 keeping to the speed limit

No worries dude.

Are you going off what a trip computer thing says or actual petrol light to petrol light/brimmed tank to brimmed tank? everyone knows commputers are prone to lying :-D

Check little thigs like tyre pressure, brake rub or even loose body panels, even small things add up to reduce efficiency.

Failing that try cleaning/replacing MAF and MAP sensors, and check turbo is working. Look at air filter condition, make sure its not restricting flow. If the car is thinking its getting enough air but actually isn't it'll still pour fuel in but won't have enough air for efficient combustion = higher fuel consumption for equivalent speed. Does the car smoke at all, especially on start up or on acceleration?

The car does not have a trip computer so the mpg is calculated from brim tank to brim tank.

The car has recently been with the dealer for nearly a week for a thorough investigation (assisted by VW I understand) at which I would have hoped all of the above were addressed. On return the dealer reported that the car was operating within "normal parameters" and that there was nothing he could do.

change your fuel filter

change your oil

change your air filter

change your oil filter

change your glow plugs

change your coolant

check your tyres are at the correct pressure

check your brakes are fitted correctly (i.e. not sticking on a little while you drive, therefore acting against the engine)

basic servicing, i'm sure you might have done these things yourself or your dealer might have... but these things generally are easy culprits for high fuel consumption. worth doing just so you can start to determine the cause. my 306 Dturbo was getting around 30mpg when i bought it... i gave it a full service, and tuned the pump slightly, and i'm now returning 45mpg on a normal run, motorway runs i think it's closer to 55mpg. just some basic servicing can go a long way.

Fisrt thing to mention is that new engines are always less efficient than 'run in' engines.

You can argue that 12,000 miles is run in all day long if you wish, but ultimately it will still be tighter than in 20,000 time. That point is an open ended discussion but worthy of note none the less.

Out of interest, here are my findings with a 2001 6N2.

When I got the car I was seeing around 48/9 mpg even on motorway runs, which was shite. I had given the car a full service when I got it so that was not an issue. Did have a faulty MAF but replaced that an still was seeing less than factory figures.

In a nutshell I now regularly see high 50s, in fact the last two tanks I have been returning 61/62ish.

The change that altered this was quite simply my driving style. Stay off boost if you can when the engine is cold, and dont over rev in each gear - it doesnt get you anywhere quicker all it does is use fuel. Use the torque of the engine, which being a diesel of course is low down in the rev range.

Those returns are on mostly local stuff with a small amount of short motorway trips included. A mate of mine has just got a 2003 1.4TDi and sees around about 54 on shorter (4/ 5 miles) local journeys driving in a similar fashion. The engine never gets to its most efficient temperature.

The point I am making is that the car will do the specificed figures, assuming nothing is wrong, but only in ideal (and slightly unrealistic for everyday driving) conditions. VW would have got those figures by sitting at 60/ 65 mpg constantly, which most likely is not a fair reflection of your journeys.

As mentioned diesels are more juicy when cold. I did 200 miles motorway and 200 miles local on one tank and saw 65.8mpg. compared to 320 miles local stuff and 80 motorway seeing 58mpg. You get my point.

Drive keeping it below 2.5k for a tank if you can and see how the economy is affected.

Then put a tenner in when the engine is up to temp and go and drain it on the motorway at 60mph and see how the economy is affected.

I think you will be supprise how much difference the above makes.

change your fuel filter

change your oil

change your air filter

change your oil filter

change your glow plugs

change your coolant

check your tyres are at the correct pressure

check your brakes are fitted correctly (i.e. not sticking on a little while you drive, therefore acting against the engine)

basic servicing, i'm sure you might have done these things yourself or your dealer might have... but these things generally are easy culprits for high fuel consumption. worth doing just so you can start to determine the cause. my 306 Dturbo was getting around 30mpg when i bought it... i gave it a full service, and tuned the pump slightly, and i'm now returning 45mpg on a normal run, motorway runs i think it's closer to 55mpg. just some basic servicing can go a long way.

Thans for your advice.

The vehicle had a service by the dealer in March and more recently a full "diagonostic" by the dealer which I was told indicated that the vehicle was operating within "normal parameters" accordingly to the dealer's computer. I assume that the diagnostic would have shown uo the need to change any of the basic service components. Until the vehicle's warranty expires I do not want to do this myself, apart from maintaining the correct tyre pressures.

Fisrt thing to mention is that new engines are always less efficient than 'run in' engines.

You can argue that 12,000 miles is run in all day long if you wish, but ultimately it will still be tighter than in 20,000 time. That point is an open ended discussion but worthy of note none the less.

Out of interest, here are my findings with a 2001 6N2.

When I got the car I was seeing around 48/9 mpg even on motorway runs, which was shite. I had given the car a full service when I got it so that was not an issue. Did have a faulty MAF but replaced that an still was seeing less than factory figures.

In a nutshell I now regularly see high 50s, in fact the last two tanks I have been returning 61/62ish.

The change that altered this was quite simply my driving style. Stay off boost if you can when the engine is cold, and dont over rev in each gear - it doesnt get you anywhere quicker all it does is use fuel. Use the torque of the engine, which being a diesel of course is low down in the rev range.

Those returns are on mostly local stuff with a small amount of short motorway trips included. A mate of mine has just got a 2003 1.4TDi and sees around about 54 on shorter (4/ 5 miles) local journeys driving in a similar fashion. The engine never gets to its most efficient temperature.

The point I am making is that the car will do the specificed figures, assuming nothing is wrong, but only in ideal (and slightly unrealistic for everyday driving) conditions. VW would have got those figures by sitting at 60/ 65 mpg constantly, which most likely is not a fair reflection of your journeys.

As mentioned diesels are more juicy when cold. I did 200 miles motorway and 200 miles local on one tank and saw 65.8mpg. compared to 320 miles local stuff and 80 motorway seeing 58mpg. You get my point.

Drive keeping it below 2.5k for a tank if you can and see how the economy is affected.

Then put a tenner in when the engine is up to temp and go and drain it on the motorway at 60mph and see how the economy is affected.

I think you will be supprise how much difference the above makes.

Thank you for your observations. My experience over the last 20 years during which I have owned a series of both petrol and diesel vehicles is as follows.

Over the 20 years my type and style of driving has changed little. Apart from the present Polo all the vehicles have returned mpgs of at least the average of the urban/combined or better. Infact our other car at present is a Vectra turbo diesel which normally achieves the combined figure or a few more mpgs on a longer run. Hence my concern for the Polo which misses the urban figure by a sigificant amount. Most disappointing was achieving only 46.5 mpg for a 300 mile trip along the A1 when trafic was light and I was able to up a constant 70mph for the vast majority of the trip.

Apart from the Polo I think that the above indicates that my driving is on the "gentle" side, generally in line with your recommendations. My motoring is essential rural being made up of 8/10 mile journeys with some dual carriageway; short trips account for less than 5%; one up with little luggage.

Most of my vehicles have achieved a small increase (5%?) in mpg after 10,000miles running in. There has usually been no further improvement to 30,000/40,000miles.

The Polo was fully serviced by the dealer in March and has had a full computer diagnostic by him since. In conclusion, comparatively the Polo has by far the worst fuel consumption of any car I have owned in the last 20 years. It is achieving very little more (<5%) than the previously 1.4 petrol Polo.

To be honest that does sound shite, as you say.

Id be tempted to stick a small amount of cash in when the fuel light comes on and then run it out at 60mph as detailed above. Do the maths and see what you have got...

Labourious I know, and should not be neccessary - but if you dont see any improvement during these conditions then it would be fair to conclude there is a problem somewhere.

It would be interesting to hear your results.

Edited 9 June, 201016 yr by StevieB