B6 Passat abnormally high mpg

andrew_ob

Ok hope someone can give me some advice.. So I just bought a 2006 B6 Passat, 1.9tdi 105bhp. Had it a few days and noticing the fuel usage is very high. On a run from roscommon to galway (via Athlone and up the M6) it averaged 7.4l/100km. I never crossed speed limit, was driving at a steady speed, and air-con was only on for maybe a 5 minute period...

That to me sounds very high. In my last car, a seat Toledo, when the air con was turned on while ticking over you would see and hear the revs fluctuate a small bit, but not in the Passat, which leads me to wonder is the air con compressor always on? Air con is working both hot and cold, but I have noticed that when I turn it off, I can still feel the air coming out of vents at whatever temperature it had been at before I turned it off (this time without the blower fans on).

Anybody got any suggestions? Car is under warranty I just want to have an idea what I might be dealing with before I go back to garage

Stinicker

Have you checked tyre pressures?

Bpmull

I assume you mean low mpg in the heading.

Firstly the trip computer is only so accurate you need to work it out using the brim method ie brim tank full of diesel drive recording mileage brim again work out l/100km using distance travelled vs fuel used.

Assuming it is getting 7.4l/100km that just under 39mpg which is a bit low. Does the car need to be serviced when we're the fuel and air filter last done they effect mpg is you don't know get them changed.

Check tyre pressure the owners manual will tell you ideal pressure but your looking at around 32 psi roughly.

Is there an a/c button or econ button for the aircon. As when a/c button is lit a/c is on where as I think it's the opposite with an econ button.

Foxhole Norman

40 or so MPG isn't too far off what that engine would do pulling a car that weight imo. If you want to get it checked though, check your tyre pressures, check for air leaks in the engine and check for the fuel/air mix from the MAF, a faulty reading can cause over fuelling.

Jesus.

Bpmull wrote: »

Assuming it is getting 7.4l/100km that just under 39mpg which is a bit low.

That's very low considering it was Motorway driving

Foxhole Norman wrote: »

40 or so MPG isn't too far off what that engine would do pulling a car that weight imo.

No way man. I get mid - late 40's Motorway in an older petrol car the same size!

Foxhole Norman

Jesus. wrote: »

That's very low considering it was Motorway driving



No way man. I get mid - late 40's Motorway in an older petrol car the same size!

You must be running it on magic or something so! My dad had a 1.9TDi Superb MK2 which isn't much heavier than the Passat and would only be doing about 45MPG or so on the Motorway, all cruise controlled too. I really wouldn't be worried about 5 or so MPG, could be any number of things affecting it.

andrew_ob

Stinicker wrote: »

Have you checked tyre pressures?

yup first thing i checked and they are spot on

andrew_ob

Bpmull wrote: »

I assume you mean low mpg in the heading.

yea sorry I meant low

Bpmull wrote: »

Firstly the trip computer is only so accurate you need to work it out using the brim method ie brim tank full of diesel drive recording mileage brim again work out l/100km using distance travelled vs fuel used.

In the process of doing this but from my experiences with these passats they are fairly close to the real thing

Bpmull wrote: »

Assuming it is getting 7.4l/100km that just under 39mpg which is a bit low. Does the car need to be serviced when we're the fuel and air filter last done they effect mpg is you don't know get them changed.

Nope car was serviced last week by VW before I bought it

Bpmull wrote: »

Check tyre pressure the owners manual will tell you ideal pressure but your looking at around 32 psi roughly.

Yea i think thats what it was, I have them set by the manual anyway

Bpmull wrote: »

Is there an a/c button or econ button for the aircon. As when a/c button is lit a/c is on where as I think it's the opposite with an econ button.

There is both of these buttons, but turning on the aircon or econ, or turning the whole thing off completely,doesnt seem to effect the mpg at all. It seems to stay at around the mid 7

Jesus.

Foxhole Norman wrote: »

You must be running it on magic or something so!

Sorry Norman, I forgot to add that I drive easy, only around 60, so that was a bit misleading. The trip com always reports 47mpg when I'm on the Motorway so its probably really more like 45mpg and if I was doing the speed limit (75) it'd be down to under 40.

Still, I think a diesel should be doing much better than that on the Motorway. I wouldn't even think that a decent return for mixed

Supergurrier

Not massively high tbh.

Biggest platform with lowest power engine.

Also thats an average. If car did alot of short trips over its life sounds about right.

andrew_ob

Foxhole Norman wrote: »

40 or so MPG isn't too far off what that engine would do pulling a car that weight imo. If you want to get it checked though, check your tyre pressures, check for air leaks in the engine and check for the fuel/air mix from the MAF, a faulty reading can cause over fuelling.

a friend of mine has a passat the exact same as mine, same engine code and everything original, he can get around 50 mpg on the motorway with cruise control set at 120km (measured by trip computer and calculated from fuel usage). I know its a heavy car and all tha but it still should be doing better. According to the trip computer its doing the same on R roads, N roads and motorways. Unless I drive at 60km/h at low revs for a long enough period, I cant seem to get l/100km under 7 l/100km

Foxhole Norman

andrew_ob wrote: »

a friend of mine has a passat the exact same as mine, same engine code and everything original, he can get around 50 mpg on the motorway with cruise control set at 120km (measured by trip computer and calculated from fuel usage). I know its a heavy car and all tha but it still should be doing better. According to the trip computer its doing the same on R roads, N roads and motorways. Unless I drive at 60km/h at low revs for a long enough period, I cant seem to get l/100km under 7 l/100km

Is this your own average or the one that's left on it since you got it? Is yours fitted with cruise control?

andrew_ob

Supergurrier wrote: »

Also thats an average. If car did alot of short trips over its life sounds about right.

That was only an average for that trip, I reset it before heading off. It only seems to be doing that at best no matter what road I'm on. Even at a fairly constant 80km/h on the N4 it only managed 7.2 l/100km over a 40 minute period

andrew_ob

Foxhole Norman wrote: »

Is this your own average or the one that's left on it since you got it? Is yours fitted with cruise control?

I reset it when I got the car last week and have only done long journeys since, and yes it has cruise control

Jesus.

There's no other way of looking at it Andy. Your mpg is well down on what it should be.

andrew_ob

I just thought it very high fuel consumption given that I have gotten up on 60 mpg when I had a similar passat for a day before. And its not my driving because I regularly got over 70 mpg on long trips in a 110 bhp Seat Toledo before, well above stated average (and yes I do understand the toledo was a good bit lighter)

Toyotafanboi

Supergurrier wrote: »

...Also thats an average. If car did alot of short trips over its life sounds about right.

this is crucial. is that figure of 7.4l across the lifetime of the car or just from that specific trip?

i know in any car i've had, if i've recently disconnected the battery (for a service or whatever) that the trip computer will reset and lose my average mpg and it will take weeks to get it back to somewhere realistic in relation to my driving style. if your car was serviced before you bought it, it may be something along those lines.

Foxhole Norman wrote: »

40 or so MPG isn't too far off what that engine would do pulling a car that weight imo.

i'm the first one to berate the almighty TDi but i'd be expecting far more than 40mpg motorway even in a 105 bhp pisshat.

we had a mk1 octavia 1.9 tdi 90bhp which weighed 1390kg's and you could crack 60mpg if you wanted to, the passat weighs 1600kgs but it has 15bhp extra so i'd expect results to be similar at least. VW's combined figure for that car was 50mpg.

Foxhole Norman

Do you get your fuel from reputable sites? I.e Topaz/Maxol or the like? I'd check the MAF, that can cause the engine to over fuel or mis fuel depending on what it's reading.

andrew_ob

Toyotafanboi wrote: »

this is crucial. is that figure of 7.4l across the lifetime of the car or just from that specific trip?

i know in any car i've had, if i've recently disconnected the battery (for a service or whatever) that the trip computer will reset and lose my average mpg and it will take weeks to get it back to somewhere realistic in relation to my driving style. if your car was serviced before you bought it, it may be something along those lines.



i'm the first one to berate the almighty TDi but i'd be expecting far more than 40mpg motorway even in a 105 bhp pisshat.

we had a mk1 octavia 1.9 tdi 90bhp which weighed 1390kg's and you could crack 60mpg if you wanted to, the passat weighs 1600kgs but it has 15bhp extra so i'd expect results to be similar at least. VW's combined figure for that car was 50mpg.

Can't tell you if its over the lifetime or not, there is two mpgs on it, one for the lifetime and one for the trip. The lifetime one should not reset even if battery is disconnected (from previous experience at least). This reading is giving it as 7.8 l/100 km.


The trip one gave my trip to galway this morning as 7.4 IIRC, which apart from the motorway also included about half hour stuck behind two lorrys at just under 80km/h

andrew_ob

Foxhole Norman wrote: »

Do you get your fuel from reputable sites? I.e Topaz/Maxol or the like? I'd check the MAF, that can cause the engine to over fuel or mis fuel depending on what it's reading.

yup get it from Maxol in my hometown all the time, and it was filled yesterday from pretty much empty so all the fuel is from there

andrew_ob

Just working out there, the fuel gauge went down by over an eight. the tank is 70 litres. So depending how accurate that is, the 7.4 l /100km actually seems quite conservative

Toyotafanboi

andrew_ob wrote: »

Can't tell you if its over the lifetime or not, there is two mpgs on it, one for the lifetime and one for the trip. The lifetime one should not reset even if battery is disconnected (from previous experience at least). This reading is giving it as 7.8 l/100 km.

well you must bare in mind that the last owner may have driven it around town for the last "x" years and it has hundreds and hundreds of driving hours recorded at low speeds doing **** mpg and it will take a long time for your motorway driving to make a meaningful impact on that figure.

a one trip average based on mostly cruising speeds (80-100km/h) returning just 7.4l - 100km or 38 mpg is ****. i could do that in my 1.8 petrol.

however, once the car sounds like it's running reasonably ok, i can almost guarantee you will be fobbed off at the dealers.

i'd satisfy myself by doing a few simple checks; tyre pressures, checking for a sticking brake calliper and check for stored fault codes etc.

then i would go about brimming the fuel tank, driving it to empty, recording the mileage taken to do so and refilling to find the litres of fuel used to accurately work out my mpg's and if they weren't a good bit north of 45mpg for mostly motorway driving given the car at hand, i'd suspect there is a problem.

andrew_ob

Toyotafanboi wrote: »

well you must bare in mind that the last owner may have driven it around town for the last "x" years and it has hundreds and hundreds of driving hours recorded at low speeds doing **** mpg and it will take a long time for your motorway driving to make a meaningful impact on that figure.

a one trip average based on mostly cruising speeds (80-100km/h) returning just 7.4l - 100km or 38 mpg is ****. i could do that in my 1.8 petrol.

however, once the car sounds like it's running reasonably ok, i can almost guarantee you will be fobbed off at the dealers.

i'd satisfy myself by doing a few simple checks; tyre pressures, checking for a sticking brake calliper and check for stored fault codes etc.

then i would go about brimming the fuel tank, driving it to empty, recording the mileage taken to do so and refilling to find the litres of fuel used to accurately work out my mpg's and if they weren't a good bit north of 45mpg for mostly motorway driving given the car at hand, i'd suspect there is a problem.

Yea I'm going to try that anyway. But I agree 38 mpg for the way it was driven this morning was terrible. Hopefully it improves a bit (or a lot)

Bpmull

Just so you know it's easy enough to reset the lifetime trip as its being called in this thread. Just hold the reset button the stalk when you are Looking at it on the screen. The difference between the two is that one resets every trip ie once the car has been off for a few hours and the other resets when you want to reset it.

Although my golf is a good bit lighter it has the same 1.9tdi 105bhp engine and I've never seen below 50 mpg to a tank everytime I check it it's normally around 52mpg doesn't go much higher. The computer reads inbetween 5-6 l/100km so I would expect the heavier passat to do 45mpg.

Toyotafanboi

Bpmull wrote: »

Just so you know it's easy enough to reset the lifetime trip as its being called in this thread. Just hold the reset button the stalk when you are Looking at it on the screen. The difference between the two is that one resets every trip ie once the car has been off for a few hours and the other resets when you want to reset it.

Although my golf is a good bit lighter it has the same 1.9tdi 105bhp engine and I've never seen below 50 mpg to a tank everytime I check it it's normally around 52mpg doesn't go much higher. The computer reads inbetween 5-6 l/100km so I would expect the heavier passat to do 45mpg.

a 3dr mk 5golf weighs 1300kgs and a b6 passat 1600kgs so a golf weighs 19% less than a passat, and you claim the worst you've ever gotten from a tank is 50mpg and this passat is getting 38mpg, so a 19% increase in weight creates just over a 24% increase in fuel consumption?

or to put it another way, stick two average weight passengers in a 3 door golf and the fuel consumption increases by a 25%. i am sceptical.

maybe, maybe around town, and i'm aware you may have a better grasp of physics than me BP, but i'm sure you'l agree that while on national/ motorway routes etc and you have gained your momentum it takes very little fuel to keep you at cruising speed so i would not expect this quantity of added weight to be almost proportional to the increase in fuel usage in a situation like this.

by that standard, a passat towing a horsebox with one average horsey occupant :pac: (car and horsebox combined weight of 3100kgs, a 97 ish % increase in weight) would see a 125 ish % increase if fuel consumption, or if 50mpg is the benchmark the car would now be returning -12.5mpg or some **** i don't even know.

Moanin

My old Passat 2006 2L Tdi would do anything from 1000 to 1,100 KMs to a full tank of diesel with about 80% motorway driving.....

Bpmull

Oh I agree with you on that tfb 38 mpg is very low. I kind of said 45 as a minimum expected average mpg. There is plenty of reps that drive them and they certainly wouldn't be driving them if they were only doing 38mpg I'm sure there are petrol passats that would that If not very close to it. I mean the first thing Id be checking is air, fuel filter and tyre pressures.

The car has been just serviced but a basic oil and filter change wouldn't change the air or fuel filter. Maybe check the book and see what was changed in the cars last service op. I suppose then you can go looking into faulty sensors and vacuum leaks and all that kind of stuff but Id start with the basic filters first. You could always get it scanned then if your sure the basics are right and see what fault codes are logged. Jacking up the wheels to ensure they are spinning freely when out of gear with handbrake off would be another good check to do.

MuppetCheck

I wonder is there a sticking calliper? Wouldn't be unknown on them.

Special Circumstances

andrew_ob wrote: »

So I just bought a 2006 B6 Passat, 1.9tdi 105bhp. Had it a few days and noticing the fuel usage is very high. On a run from roscommon to galway (via Athlone and up the M6) it averaged 7.4l/100km.

andrew_ob wrote: »

Just working out there, the fuel gauge went down by over an eight. the tank is 70 litres. So depending how accurate that is, the 7.4 l /100km actually seems quite conservative

I'd say a bit early to tell. Maybe disconnect battery and have the car re-learn various trims to suit your driving rather than the last owner?

Truckermal

The tank don't hold 70 litres the most I ever put in mine is 65 and that was seriously low. Anyway Check the air filter as it may not have been changed.

John T Carroll

Moanin wrote: »

My old Passat 2006 2L Tdi would do anything from 1000 to 1,100 KMs to a full tank of diesel with about 80% motorway driving.....

That sounds about right, if you had only 5 ltrs tank remains (warning light on?) this would equate to a consumption of 6.19 Ltrs/100Kms or 45.6 MPG.

Moanin

John T Carroll wrote: »

That sounds about right, if you had only 5 ltrs tank remains (warning light on?) this would equate to a consumption of 6.19 Ltrs/100Kms or 45.6 MPG.

Yeah light would come on top refill

RandomUsername

The water temperature sensor is a known issue in bags of that era and a fairly cheap fix. It would be worth fitting a new one as they do bring down the mpg a bit when they get tired.

Sorry to butt in, but I got a 08 Passat last week...1.9TDI. How do I get mpg, fuel consumption etc up on the dash. At the moment, I have the time, temp, total mileage and trip mileage?

John T Carroll

RandomUsername wrote: »

The water temperature sensor is a known issue in bags of that era and a fairly cheap fix. It would be worth fitting a new one as they do bring down the mpg a bit when they get tired.

Agreed, a faulty temperature sensor can cause all sort of fueling problems but the two or three that failed on my VWs just stopped reading, my '00 Bora had two temperature channels in the one sensor, one went to the instrument panel and the other to the ECU, if the former went faulty it had no effect on the ECU and didnt show up as a fault in the diagnostics, if the channel to the ECU failed then the fault showed up in the diagnostics but no where else. I think all VWs from maybe 03? onwards have only one channel so there is a fair chance that you would notice it via the instrument temperature gauge, but yes, its worth considering changing it.
The engine is also possibly running colder than normal due to a faulty thermostat, remember that the temperature gauge will still read 90C even if the coolant is only =or>75C. Its relatively easy to check this but be careful where you put your hands/fingers, start off with a completely cold engine and either let the engine idle or drive off but make sure that you are on a road where you can pull into the side safely. Just before the temperature gauge indicates 90C which is truly only 75C, feel the top radiator hose, try and feel it ABOVE where the expansion bottle vent joins it (if indeed it does) and it should be practically stone cold as the thermostat doesnt start opening until around 85C, it will be very apparent if in fact the thermostat is passing.
Apoligies for being a bit long winded but this just might point you in the right direction for little or no cost.

slookie

slookie wrote: »

Sorry to butt in, but I got a 08 Passat last week...1.9TDI. How do I get mpg, fuel consumption etc up on the dash. At the moment, I have the time, temp, total mileage and trip mileage?

Can anyone help with this?? Driving me cracked.

RandomUsername

slookie wrote:

Can anyone help with this?? Driving me cracked.

If it is possible on your instrument cluster (I'm not sure if it is) It will need to be programmed by vcds a vag diagnostics tool/programme. A good specialist should be able to do it.

John T Carroll

slookie wrote: »

Can anyone help with this?? Driving me cracked.

Daughter has 08 1.4 TSI but instrument display should be similar, will ask her tonight when I see her and pass on any info, if I have any.

groovie

slookie wrote: »

Can anyone help with this?? Driving me cracked.

Is there a toggle on the outside edge of the wipers arm?

Bpmull

slookie wrote: »

Can anyone help with this?? Driving me cracked.

Flick through the menu using the up down switch at the end of the wiper stalk it would be the same type switch used for cruise control on the left stalk.

If it is an extremely low spec it won't have the on board computer although I thought all passats of that year would have it. Basically if the temperature is displayed top right corner it doesn't have on board computer. If temperature is displayed in the centre of the screen it does have it.

Moanin

groovie wrote: »

Is there a toggle on the outside edge of the wipers arm?

It depends on the spec. Is your car the basic, comfort line or Highline model?

redlead

Moanin wrote: »

It depends on the spec. Is your car the basic, comfort line or Highline model?

Only B6 Highlines have this. I have an 07 Comfortline and the trip computer is way more basic than my 02 Yaris Banger

It's the comfortline model. Id say it doesnt have it.

Joe 90

Toyotafanboi wrote: »

a 3dr mk 5golf weighs 1300kgs and a b6 passat 1600kgs so a golf weighs 19% less than a passat, and you claim the worst you've ever gotten from a tank is 50mpg and this passat is getting 38mpg, so a 19% increase in weight creates just over a 24% increase in fuel consumption?

or to put it another way, stick two average weight passengers in a 3 door golf and the fuel consumption increases by a 25%. i am sceptical.

maybe, maybe around town, and i'm aware you may have a better grasp of physics than me BP, but i'm sure you'l agree that while on national/ motorway routes etc and you have gained your momentum it takes very little fuel to keep you at cruising speed so i would not expect this quantity of added weight to be almost proportional to the increase in fuel usage in a situation like this.

by that standard, a passat towing a horsebox with one average horsey occupant :pac: (car and horsebox combined weight of 3100kgs, a 97 ish % increase in weight) would see a 125 ish % increase if fuel consumption, or if 50mpg is the benchmark the car would now be returning -12.5mpg or some **** i don't even know.

Don't forget frontal area as well as weight. Both matter and at a steady speed on the motorway frontal area difference will be important.

John T Carroll

John T Carroll wrote: »

Daughter has 08 1.4 TSI but instrument display should be similar, will ask her tonight when I see her and pass on any info, if I have any.

Her car doesnt display them either as its the Comfortline.

Bpmull

Surly a comfortline b6 passat has a trip computer that reads, l/100km, driving time, range, distance travel, average speed etc.

redlead

Bpmull wrote: »

Surly a comfortline b6 passat has a trip computer that reads, l/100km, driving time, range, distance travel, average speed etc.

No

John T Carroll

Bpmull wrote: »

Surly a comfortline b6 passat has a trip computer that reads, l/100km, driving time, range, distance travel, average speed etc.

I'm quite surprised as well but my daughter says no (as well as numerous other posters here) a 2000 comfortline Bora has all these but I suppose its typical VW, when they finally condenscended to fit a petrol gauge to the old air cooled Beetle it didnt work as it consisted of a cork and a bit of bent wire mechanically connected to the gauge.