[andymac]

Right,

Now Ive sorted my blowing maniold I still have one problem which I had put down to my leaky exhaust manifold.

Car is 2006 non dpf v10 60000 miles.

I cannot get over 22 mpg, on short runs Im lucky to see 14 around town. Im driving like a Granny as well as I keep getting caught speeding!!

a full tank 100 ltrs (more like 90-95) will at best get me 300 miles with mixed urban and roads

Its been scanned no faults, been serviced properly.
Air filters are clean
Tyre pressures are 50 psi front
45 psi rear
no brakes are binding
The webasto is doing its job, I replaced its pump last year
The thermostat was stripped and checked whilst the engine was out.

What should the Mafs be reading?
What should the temperature gauges be reading?
Could it be injectors?
Could it be timing (I cant see how its gear driven)
The manifolds don't look clogged

Anything else I can check, I don't think its boost leaking but its hard to check on this engine. Can I pressurizer the system to check?

 

[andymac]

Oh and before anyone says its a v10 what do you expect, its not that Im expecting it to be great its just I know this is bad so I want to know whats causing it.

 

[ToolmanJohn]

How much diesel does that Webasto heater use... Same fuel economy when it is not used?? Check the Webasto support page (if they have one) and see how much fuel it might use each time it is in operation.

You might try running a diesel additive for a few tanks to see if it cleans the injection system? All I can think of beyond needing extensive diagnostics.

 

[zegm]

In the summer I average 18/19mpg and in the winter I average 20/21mpg and I have a lead foot so it is not because it is a V-10. But other than that I can't help you. Is it locked in low gear? Best I got.

 

[zegm]

Oh I do use a Lubro Moly diesel additive and the mileage went up 1.5 mpg and you get a noticable power increase. IDParts has it.

 

[Horton]

I cannot get over 22 mpg, on short runs Im lucky to see 14 around town

We get 21-23 combined in our V10 (with DPFs). Our in-town average is 18mpg in summer; when the air temp dips below zero in MN, MPG can get to 15-17 in-town. Highway climbs to 25-26 on trips over 100 miles going to speed limit.

 

[andymac]

The webasto is pretty clever it wont over fuel it will cut out and I dont run it aside from when the car runs it. If anything it should improve MPG as it gets the engine upto heat quickly.

I will to be sure pull thee fuse on it tomorrow just to check.

 

[andymac]

can you tell me what the ingredients are of Lubro Moly diesel additive Ill see if I can get an equivalent in the UK....

How many miles do you guys get out of a tank?

 

[Eugene-Dave-1]

Looking at 2005 to 2007 V10 statistics on fuelly.com, the lowest average MPG is 14.3, highest average MPG is 20.4. Those numbers should be reliable since they're calculated based on odometer reading and measured amount of fuel used. Are you really that far off?

 

[Baltimore Touareg]

OP, what MPG are you used to doing city/hwy?

 

[Mike N]

He's in the UK so don't forget that an imperial gallon is 1.2 US gallons. Divide his mileage by 1.2 to get US MPG and you'll start to see the magnitude of the issue. 22 MPG in the UK is 18 MPG in the US. 14 is 11.6 in the US. Those are bad numbers.

 

[andymac]

Urban 15 mpg Highway is hard to tell as our roads are so stop start I will have to check tommorow.

 

[andymac]

He's in the UK so don't forget that an imperial gallon is 1.2 US gallons. Divide his mileage by 1.2 to get US MPG and you'll start to see the magnitude of the issue. 22 MPG in the UK is 18 MPG in the US. 14 is 11.6 in the US. Those are bad numbers.

Thanks Mike, Id forgotten about that! I knew it was bad.

 

[zegm]

can you tell me what the ingredients are of Lubro Moly diesel additive Ill see if I can get an equivalent in the UK....

How many miles do you guys get out of a tank?

Lubro/Lubri Moly is a German company you should be able to get it.
Here is the link: LIQUI MOLY - Motor Oils, Additives, Car Care - Products - Super Diesel Additive

While on the Lubro Moly website I came across this: LIQUI MOLY - Motor oils, Additives, Car care - DPF Cleaner Kit This is a DPF cleaning kit! I am going to be the first one to give this a try!

I get almost 500 miles out of a tank during the winter. That is with the additive. And I like to accelerate hard but once up to speed I always use the cruise control. I did an experiment one day and I could not match the fuel economy at the same speed with my right foot as the cruise control.

Liqui Moly has a couple of other additive cleaners that are worth looking into.

 

[andymac]

Great Ill try some tomorrow , I recognize the Liqui Moly brand so probably can get it.

SLightly worried that any additives may mess with the injector seals, any opinions anyone?

 

[zegm]

Great Ill try some tomorrow , I recognize the Liqui Moly brand so probably can get it.

SLightly worried that any additives may mess with the injector seals, any opinions anyone?

I have been using their products for years without any issues, but mainly their Gasoline Jectron Fuel Injection cleaner in my BMWs.
LIQUI MOLY - Motor Oils, Additives, Car Care - Products - Jectron

 

[Eugene-Dave-1]

I must be dense. Even refactoring for UK gallons (d'oh!), OP's numbers seem not all that far out of whack if there are a lot of short trips involved. My V6 TDI MPG gets dragged down if I'm doing any meaningful amount of city driving.

Never mind. Nothing to see here... *shrug*

 

[Niner]

I must be dense. Even refactoring for UK gallons (d'oh!), OP's numbers seem not all that far out of whack if there are a lot of short trips involved. My V6 TDI MPG gets dragged down if I'm doing any meaningful amount of city driving.

Never mind. Nothing to see here... *shrug*

Ditto, nothing to see here. Pretty much the norm for a V-10.

 

[Mike N]

My short trip MPG (less than 10 miles) is right around 14 MPG (16.8 in the UK). Longer trip (50 miles+) is over 20 MPG (24 in the UK). Currently my long term mileage displayed on the MFD is just under 19 MPG over 3400 miles (22.8 in the UK). I would say there is something wrong or at least inconsistent with the OP's mileage. Oh, and I don't baby my V10. Perhaps that's the problem take that puppy out and give it a good old 'Italian Tune Up'.

 

[JMosch]

I can never get more than 14mpg in the city and 21 on the highway at best.