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[jonnycool]

The most economical cruising speed for any car is the slowest you can go in top gear, anything above this and you are wasting energy on air resistance. if you can get behind a large vehicle so that you can slipstream, all the better.
   80 mph would never be considered an economical speed to be travelling at; even if you reduced your speed to 70mph you'd be using significantly less fuel

Jon

[Kevin Wood]

The most economical cruising speed for any car is the slowest you can go in top gear, anything above this and you are wasting energy on air resistance. if you can get behind a large vehicle so that you can slipstream, all the better.
   80 mph would never be considered an economical speed to be travelling at; even if you reduced your speed to 70mph you'd be using significantly less fuel

Jon

Agreed, except that the engine speed needs to be high enough for it to be working efficiently. Normally the bottom end of the torque delivery is best so 2K RPM or a little higher for the V6. Any slower and the engine is labouring. It may have fewer losses in terms of friction but it won't be burning fuel as efficiently.

Mine certainly drinks more fuel as speeds raise. 36 MPG at 60/65, 33 at 70, 28-30 at 80 and so on.

I've never survived the boredom of driving slower than 65 to get a meaningful reading - sorry.

Kevin

[feeutfo]

I find judging throttle off but not breaking helps, ie don't stay on the power all the way to the junction and break hard ish. Rather throttle off early using the auto boxes tendency to roll on with minimal engine braking, and hence minimal fuel, and judge it to give minimal braking effort when at the junction. Keeps me amused when I can't crack on due to traffic, then waste it all when the road clears. 

[duggs]

Completely agree with Chrisgixer...Thats how i drive my 3.0 and in fairness she delivers better mpg than my previous 2.5.

Combo between dual carriageway and town driving for work, never drops below 25 on ave.

[Kevin Wood]

Completely agree with Chrisgixer...Thats how i drive my 3.0 and in fairness she delivers better mpg than my previous 2.5.

Combo between dual carriageway and town driving for work, never drops below 25 on ave.

That's how I was driving following TheBoy and Chrisgixer on Saturday, as my Trade Club brake pads felt like blocks of wood.

Kevin

[feeutfo]

Completely agree with Chrisgixer...Thats how i drive my 3.0 and in fairness she delivers better mpg than my previous 2.5.

Combo between dual carriageway and town driving for work, never drops below 25 on ave.

That's how I was driving following TheBoy and Chrisgixer on Saturday, as my Trade Club brake pads felt like blocks of wood.

Kevin

Oe pads Kev, little dust good feel, no squeak, and I'm told will last much longer than tc pads...no fade on saturday. I presume your tc pads are a little thin?

[Kevin Wood]

Completely agree with Chrisgixer...Thats how i drive my 3.0 and in fairness she delivers better mpg than my previous 2.5.

Combo between dual carriageway and town driving for work, never drops below 25 on ave.

That's how I was driving following TheBoy and Chrisgixer on Saturday, as my Trade Club brake pads felt like blocks of wood.

Kevin

Oe pads Kev, little dust good feel, no squeak, and I'm told will last much longer than tc pads...no fade on saturday. I presume your tc pads are a little thin?

Nope. Not been on there that long (although probably longer than I think TBH).

Everyone in both kit car and MX5 circles seems to rave about Mintex 1144 pads. £98.20 inc.VAT an axle set for an Omega though.

Kevin

[2woody]

two issues - is it auto ? and what diff has it got.

I have two similar cars, as follows.......

MV6 3.0 estate ex-plod auto with 4.22 LSD - manages just over 20mpg at best

Elite 3.0 manual - standard diff - can't get it below 30mpg

yours is ex-plod I'm certain, so check the diff out. If you're not sure, then record the speed you're doing at 3000 revs in top (satnav), send me a pm with your tyre size and I'll calculate it for you.

[mrjimbo]

Sorry i haven't replied before but been without PC for last 24hrs   

two issues - is it auto ? and what diff has it got.

I have two similar cars, as follows.......

MV6 3.0 estate ex-plod auto with 4.22 LSD - manages just over 20mpg at best

Elite 3.0 manual - standard diff - can't get it below 30mpg

yours is ex-plod I'm certain, so check the diff out. If you're not sure, then record the speed you're doing at 3000 revs in top (satnav), send me a pm with your tyre size and I'll calculate it for you.

It is indeed ex plod but the issue isn't diff related as i have achhieved 32/33mpg in the past driving in exactly the same way.



Posted by: chrisgixer Posted on: Yesterday at 06:53
something not right imo. Has the multiram issue returned possibly? Also concider cam belt timing, blocked exhaust etc

I don't think the multiram problem has returned as it seems to be driving OK and doesn't seem to be holding back or slugish at all so i doubt the exhaust is blocked, though i could be wrong. As for the cam belt/timing, last time i had problems with the belt it ran like a dog but it seems to be smooth enough at the moment.

I'll have a check of the exhaust and cambelt at the weekend and report back   

 

[mrjimbo]

If when i check the cambelt at the weekend would it be OK to alter the cam timing if i find it's not spot on without doing a full cambelt change ?

It was 2years and 12000miles since it was last done 

[feeutfo]

If when i check the cambelt at the weekend would it be OK to alter the cam timing if i find it's not spot on without doing a full cambelt change ?

It was 2years and 12000miles since it was last done 

Ah, thought the cam belt had been done recently, appologies. If your getting variation in fuel economy, as opposed to continually poor, then not likely to be cam belt unless there is something very wrong, in which case the belt would have failed by now. Was it set correctly with a locking kit? No need to change the belt if adjusting.

Did The Boy run a full diagnostic at oxford? What was the fuel trim error? (although I'm sure he would have said if there was a problem)  :-/    

[mrjimbo]

The cambelt was set as per instructions and used a locking kit which i borrowed from a friend of a friend so as said probably not a cambelt issue.

TheBoy only lowered the idle speed down to factory setting as plod had raised it(probably due to alternator not coping with all the equipment at idle ?) and checked the multirams were functioning, which they are now after unpluging them several times (probably dirty plug coonection). I don't think he did anything else, I'm sure he'll be along soon to confirm 

It seems to drive OK with nothing untoward but i just can't get my head round why i only got 21mpg on Sunday.
I have in the last couple of weeks changed the Autobox fluid, cleaned the breathers, removed the plenum to check the 'O'rings were sound, sorted the multirams, changed the antifreeze, had the aircon HP service valve changed and regassed. The brakes aren't binding and there's no vacum leaks(Vacum tank will retain vacum for 24hrs+) and the exhaust isn't heavily sooted either. It's a mystery at the moment but i will get to the bottom of it   

[feeutfo]

The cambelt was set as per instructions and used a locking kit which i borrowed from a friend of a friend so as said probably not a cambelt issue.

TheBoy only lowered the idle speed down to factory setting as plod had raised it(probably due to alternator not coping with all the equipment at idle ?) and checked the multirams were functioning, which they are now after unpluging them several times (probably dirty plug coonection). I don't think he did anything else, I'm sure he'll be along soon to confirm 

It seems to drive OK with nothing untoward but i just can't get my head round why i only got 21mpg on Sunday.
I have in the last couple of weeks changed the Autobox fluid, cleaned the breathers, removed the plenum to check the 'O'rings were sound, sorted the multirams, changed the antifreeze, had the aircon HP service valve changed and regassed. The brakes aren't binding and there's no vacum leaks(Vacum tank will retain vacum for 24hrs+) and the exhaust isn't heavily sooted either. It's a mystery at the moment but i will get to the bottom of it   

That's the spirit Jim. Wish we had paid more attention at oxford now.  :-/

[mrjimbo]

The car seems to drive OK so there didn't appear to be anything that needed to be looked at other than the idle speed and check the multiram solenoids were working as they should, and they were given a clean bill of health 

21.4mpg on a run ain't good though so im going to check the cam timing and exhaust for blockages as you suggested.

Anyone got some pictures of the timing marks on the cam wheels and which marks are the right ones ?
 I've lent my "book of lies out" and won't be able to get it back until Tuesday and i won't be able to get a Cambelt DVD in time for Saturday.
I've got a locking kit 

[TheBoy]

Completely agree with Chrisgixer...Thats how i drive my 3.0 and in fairness she delivers better mpg than my previous 2.5.

Combo between dual carriageway and town driving for work, never drops below 25 on ave.

That's how I was driving following TheBoy and Chrisgixer on Saturday, as my Trade Club brake pads felt like blocks of wood.

Kevin

Oe pads Kev, little dust good feel, no squeak, and I'm told will last much longer than tc pads...no fade on saturday. I presume your tc pads are a little thin?

Hmmm, I was on TC cheapo pads, no issues at all here.  I agree cheapo TC pads are dusty (esp the rear if you make a lot of use of TC ), but nothing we did on Sat should have caused any issues for any pad  :-/