22mpg....ouch

[Guest coliff]

Blimey, just drove down from Chorley to Leicester in my newly aquired 1997 2.0 GLX Gal and got 22 MPG for constant motorway speed (70mph...ish). Surely this is not right ! Just had the car serviced, i was on my own in the car and yes, it was in 5th gear :)

 

I was expecting at least 30 mpg for motorway use. Any thoughts......the car had been stood for a week and i have just sqeezed another

[seatkid]

I think upper twenties at least, if its running rich, could be lambda probe is duff, but check the simple things first like a blocked air filter. Is it lumpy? Could be plugs/leads/coil.

[Ivor_E_Tower]

Seems a little heavy on juice, but not too bad really - don't forget that the Galaxy has a large frontal are - loads of air to push aside, and therefor also loads of drag, especially at speed. The difference in fuel consumption between 56 and 70 mph is much greater than the "official" government figures would have you believe. The 2 4-cylinder petrol Galaxies that I had use of, before buying a diesel, averaged 22 to 25mpg on the motorways and urban driving.

[Guest MATT]

just get a diesel.

 

matt :lol:

[sip]

My 2.0 GLX Auto gives me about the same fuel consumption. Just about half a tankful from Leicester - Bradford - Leicester at speeds varying from 60mph to (no cops on this site I hope) 90mph.

[Guest MATT]

90mph.

TUT TUT.

http://www-atdp.berkeley.edu/1623/students/simon/homer-mug.gif

 

MATT :lol:

[Ivor]

At the weekend I drove from Manchester down to Hastings and back (280 mile each way)

50.8 MPG going at avg 68MPH on cruise.

44.0 MPG coming back at avg 71MPH on cruise.

 

Above 70MPH all cars start to drink fuel because of the air they have to push out of the way.

 

I filled up when I set off, and I'm just starting to go in the red now :huh: , after 2.1/2 days back at work.

 

Get a Diesel!

[Andrew T]

I'd mostly agree with you, but I don't think it's quite as clear cut as you suggest because of the effect of head and tail winds. But somewhere between less than 70 and 80 there is a point where the Galaxy starts drinking a lot more fuel in relation to a small increase in speed. Problem is if you don't have a Fuel computer you won't know where that point is......

 

We had strong northerly winds up here last weekend, perhaps that had an effect on your fuel consumption coming back oop north ?

[Ivor_E_Tower]

... somewhere between less than 70 and 80 there is a point where the Galaxy starts drinking a lot more fuel in relation to a small increase in speed.

Aero drag is proportional to the square of the speed. Doubling your speed quadruples the drag (ie 2 squared is 4) so the faster you go, the much higher the drag forced become.

[maglite]

Hello, I've got a 2.0 GLX 1996 'N' reg auto and mine gives about 30mpg if I keep it at a constant 70. Only a few days ago did I change the plugs and leads. The Plugs I used were platinum ended ones Made in Japan. They are the NGK VX Platinum BKR6EVX. After changing the leads and the plugs, the car responded a lot better from before. :lol:

[NikpV]

Aero drag is proportional to the square of the speed. Doubling your speed quadruples the drag (ie 2 squared is 4) so the faster you go, the much higher the drag forced become

 

I thought it wasn't that simple - turbulent/laminar flow can produce different drag amounts and I have some vague memory from a thermodynamics course (25 years ago) that at higher speeds it can become proportional to the cube of the velocity. :lol:

[Guest MATT]

I thought it wasn't that simple - turbulent/laminar flow can produce different drag amounts and I have some vague memory from a thermodynamics course (25 years ago) that at higher speeds it can become proportional to the cube of the velocity. :D

:lol: :o :o :D

[Ivor_E_Tower]

I wouldn't get too hung up about this; there is also air resistance, tyre drag/friction, mechanical friction etc etc to consider ....... :o :lol: :o

[greg_68]

Blimey I've stumbled upon an open university course on vehicle aerodynamics. :o

 

When it says technical section I didn't think it was literally that. :lol:

[faded-fish]

From what I recall at about 55mph, approximately half of your fuel consumption is to combat wind resistance (any faster and the wind resistance consumption is greater still). That is why the Americans have/had a 55mph speed limit - it was set during one of their many oil shortages to economise.

 

Getting a Tdi would be my preference for increasing mpg, but if you're on a low budget (as I was/am) affordable models are like rocking horse manure :lol: (very rare!!!) and if you do find one, it will either be sold before it hits the forecourt or it will have travelled half way across the galaxy!!!

[seatkid]

Blimey I've stumbled upon an open university course on vehicle aerodynamics. :o

 

When it says technical section I didn't think it was literally that. :lol:

Here's a link to the open university listing all the formula associated with drag factor, fuel consumption etc.

 

Pay attention all you at the back, tomorrow there will be a written test....... :o

[Sharan Carat]

I'm off tomorrow wnd my mum has written a note!!!

[NikpV]

but Sir I was away when you did that so I can miss the test can't I <_ :huh:>

[Guest asylumhouse]

one add one equals three? :huh: , two add two equals five??? <_< .......

 

nah, i wont qualify for this technical section uni course......... but i,ll make a bloody good politician :D :D

[GSMGuy]

Asylumhouse had stumbled upon the secret formula used by dealers to calculate labour charges!!!

 

Mike

[Ivor]

At the weekend I drove from Manchester down to Hastings and back (280 mile each way)

50.8 MPG going at avg 68MPH on cruise.

44.0 MPG coming back at avg 71MPH on cruise.

 

Above 70MPH all cars start to drink fuel because of the air they have to push out of the way.

 

I filled up when I set off, and I'm just starting to go in the red now :huh: , after 2.1/2 days back at work.

 

Get a Diesel!

Hmm, fifth day back at work, must fill up tonight! :huh:

[iainkirk]

Drove the Galaxy from Carlisle to Ullapool last week.

 

Two bikes on the roof and a boot full of stuff (although 2 seats left in garage)

 

My normal average mpg from the computer is 35 ish (lead boots)...

 

On this journey I acheived......

 

26 mpg :huh:

 

EVEN though about half the journey was on single carriageway 60mph scamera-infested A9 etc

 

So, the moral of the story is:

 

If you want your TDI to have the performance and fuel consumption fo a 2.3 petrol, fill it with stuff and put two bikes on the roof :huh: