41.5 mpg

**cameron** · Sunday 24th May 2009, 23:47

Went a round trip from Oldham - Blackpool today

A Round trip of 110 miles.

Cruising at 65 - 70 mph my average mpg shown 41.5mpg

For a car that weighs nearly a tonne and a half and cruising at motorway speeds thats unreal.

Long live the 304'D T5

**AlanG** · Sunday 24th May 2009, 23:54

That just doesn't sound possible buddy.....Not doubting your word but is your info centre doofry taking drugs????

**t5 pete** · Sunday 24th May 2009, 23:56

Im sure my average mpg is totally wrong it never goes above 23mpg but when i work it out with how much fuel ive used to how many miles i do i get quite good mpg so god know

**cameron** · Sunday 24th May 2009, 23:57

Try it for yourself matey

Nothing wrong with the info center on my car.

Cruise at 65 - 70 mpg for 40 miles and see what it shows i think you will be pleasently surprised

Dont get me wrong after i went to Bolton and back but i was giving it some and even at 70 + i was still getting 29 + mpg

**AlanG** · Monday 25th May 2009, 00:02

Can't beata Rica! Good to hear,wi a bit o luck I'll get a decent run in mine soon. Normally averages 33-35mpg but short runs

**pookie** · Monday 25th May 2009, 18:03

Lee,
May be worth checking your speedo trip against a measured mile. I know mine is not accurate, and therefore don't really believe what my info centre tells me with regard to fuel consumption.

Pookie

**p fandango** · Monday 25th May 2009, 18:34

Originally Posted by pookie

May be worth checking your speedo trip against a measured mile. I know mine is not accurate, and therefore don't really believe what my info centre tells me with regard to fuel consumption.

speedo's are programmed to have an error, i know on newer Volvo's there is a secret menu to display the correct speed which from what i've seen is spot on (it will be wrong if running non-original tyre sizes tho) & would of thought the info/trip computers use the correct figure to work everything out

**pookie** · Monday 25th May 2009, 20:25

Originally Posted by p fandango

speedo's are programmed to have an error, i know on newer Volvo's there is a secret menu to display the correct speed which from what i've seen is spot on (it will be wrong if running non-original tyre sizes tho) & would of thought the info/trip computers use the correct figure to work everything out

I can't understand ( as an motor engineer ) how it can do this, other than a G.P.S. link-up. The newer cars may have this but the older 850's I very much doubt it.

Pookie

**p fandango** · Monday 25th May 2009, 21:05

Originally Posted by pookie

I can't understand ( as an motor engineer ) how it can do this, other than a G.P.S. link-up. The newer cars may have this but the older 850's I very much doubt it.

the whole speedo system is still electric instead of the old cable drive, what i'm saying is the system actually measures a more accurate speed than it displays so would of thought the trip computer would use that figure. The 850's are more than capable of this sort of stuff & have some very trick electronics in there (like the rev-counter using a 4cylinder pulse instead of a 5cylinder one)

**shaun850** · Monday 25th May 2009, 21:40

Get your afr's checked

I did gloucester to plymouth and back 400 odd miles and got 34mpg

**polredt5** · Monday 25th May 2009, 22:01

I did 415miles on saturday and i managed 28.3 avg.That was with two sticky calipers though,guessing low 30s if all had been well.

**cookie** · Monday 25th May 2009, 22:25

most electronic speedo's read the pusles from the ABS, so if tyre size is correct speed can be measured almost exactly. If you read speed from your OBD2 port, and put in wheel size, and tyre size it will read almost perfect correct speed, with a tolerance of fractions of a percent in a straight line

**pookie** · Monday 25th May 2009, 23:11

Originally Posted by cookie

most electronic speedo's read the pusles from the ABS, so if tyre size is correct speed can be measured almost exactly. If you read speed from your OBD2 port, and put in wheel size, and tyre size it will read almost perfect correct speed, with a tolerance of fractions of a percent in a straight line

Now I understand that. Can this be done on the old 850's? There is so much diversity in wheel and tyre sizes it would be useful to know.

Pookie

**T5arrrgghh** · Tuesday 26th May 2009, 00:17

wow if i get 28 i have been driving like a saint! i get 20 on the runs to the forest for biking at the moment! ah well. and as for the speed thing i have tried and checked it against a few sources and its all out but then i am on 40 profiles but the average speed seems a bit more accurate than the dash indicator, but hey they are just indications!!

**cameron** · Tuesday 26th May 2009, 23:15

Used my sat nav today to judge the speed and there was a difference of 4 - 5mph

If thats right then i was only doing 60 - 65mph and not the stated 65 -70mph, so maybe thats where the higher mpg has come from

**850 2.5 10v** · Wednesday 27th May 2009, 12:03

Brim the fuel tank until its so full you can see the fuel.

Drive 100 miles and then brim it again.

Record the number of litres used to re-fill.

Do the maths and you'll know for sure what mpg you are doing.

Cheers

**flyingbrick** · Wednesday 27th May 2009, 13:13

Originally Posted by cameron

Used my sat nav today to judge the speed and there was a difference of 4 - 5mph

If thats right then i was only doing 60 - 65mph and not the stated 65 -70mph, so maybe thats where the higher mpg has come from

Hi Lee.

It will be because you have put 17" wheels on buddy.....

the speedo will be out by like you said between 5 mph and 8 mph....

**p fandango** · Wednesday 27th May 2009, 15:02

Originally Posted by cameron

Used my sat nav today to judge the speed and there was a difference of 4 - 5mph

If thats right then i was only doing 60 - 65mph and not the stated 65 -70mph, so maybe thats where the higher mpg has come from

speedo's by law can read upto 10% under (never over) & tbh have never known any car/make to read spot on.

My 850 (on 18's) reads 5mph out across the whole range, while my S60 (on standard wheels/tyres) reads 7mph out

as i've said before i suspect the fual computer would use the acurate MPH figure & not from the speedo

**AndysR** · Wednesday 27th May 2009, 21:48

I think it's great that your getting those fuel efficency readings from your car Cameron. My brother achieved similar figures with his S70R on a similar run. However hasn't acheived those figures since he had his injectors cleaned and two were found to be faulty. The reason for his optimistic fuel consumption reading was the engine was running lean as a result of the two faulty fuel injectors, the standard lambda control can only monitor afr across the 5 cylinders not at each cylinder at any given time and will then adjust all to suit, running lean isn't ever good for an engine especially an engine utilising forced induction.

If I were you I would get the AFR's checked and the I would certainly advise you get the fuel injectors cleaned/flow checked.

**gtiteen** · Wednesday 27th May 2009, 23:55

i have had a trip computer reading of 38 on a trip from eastourne to gatwick in my old rica 304 850 on standard rims. Was deliberately trying to dive economically. I imagine there is some innaccuract but still reckon must have been 36 odd which i was happy with. well compared to my current 18mpg lol.