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Model specific boards => Golf mk5 => Topic started by: ifti on 03 April 2009, 14:28

Title: MPG - How accurate is computer??
Post by: ifti on 03 April 2009, 14:28
On a spirited drive, you can almost see the needle moving down to the empty mark! lol

However, I just went out and was stuck mainly down the A127, which has average speed cameras at 50 and 70mph, pretty much all long it.
The entire trip had only a few minutes or so through a town, and the rest on motorway or A127 Dual carriageway.

Filled up to the brim, and then drove like a grandad because of the cameras, and to see what I could get out of the car.
Throughout the trip, mpg went high and low. However, I was shocked to see 133mpg at one point! (steady downhill) Although it only for a second!

After the entire trip (around 70 miles), I checked the average mpg as I parked up, and was suprised to see 36.8mpg!!
After the 70 miles it also still thinks I have another 375 miles until next refuel!  :grin:

How accurate is this thing? lol

I guess it all is down to how you drive!
Title: Re: MPG - How accurate is computer??
Post by: smartypants on 03 April 2009, 14:41
Not got my Golf yet so can't comment on your car - but in my experience driving various cars from BMW to Ford to Porsche's all trip computers are very inaccurate.

The most accurate way to measure your MPG is to fill up, reset the trip computer, do your trip and then fill up again - noting the amount of fuel and the reading on your trip computer - and then do your maths :D

Title: Re: MPG - How accurate is computer??
Post by: DJGTi on 03 April 2009, 17:11
I've checked the computer against actual fill ups a couple of times and found it to be within 0.1 mpg over a full tank. I was amazed as I've seen some that are over 10% out.
Title: Re: MPG - How accurate is computer??
Post by: ifti on 03 April 2009, 18:19
Yup, I reset my trip meter when I filled up. Habit I guess!
Will work out what I get once I refill again - hopefully it will get me through the week!
Title: Re: MPG - How accurate is computer??
Post by: stealthwolf on 03 April 2009, 18:45
Also remember to reset the average mpg after filling up.

I've found 'miles remaining' or 'range' to be dependent on your last average mpg reading, so if your average mpg was 20, your 'range' on a full tank will be lower than if your mpg was 40.

I've found the range to vary from as low as 300 miles to as high as 375 miles (and then stay at that reading for 25 miles because I've been cautious).
Title: Re: MPG - How accurate is computer??
Post by: Jkctr on 03 April 2009, 18:51
I had the one that reads while you drive show 99mpg  :laugh:

The average is accurate, dont believe the 'while you drive' one  :wink:
Title: Re: MPG - How accurate is computer??
Post by: ifti on 03 April 2009, 18:59
How do you reset the average mpg reading?
Title: Re: MPG - How accurate is computer??
Post by: Jkctr on 03 April 2009, 19:08
It does it after you stop and does a new one for the next journey.
Title: Re: MPG - How accurate is computer??
Post by: ifti on 03 April 2009, 21:30
It does it after you stop and does a new one for the next journey.

Yeh I thought it had reset when I left this morning - nevertheless, was well chuffed to see I could get above 35mpg out of it when Im really strapped for cash!! Need to wait for next pay day so cant put my foot down to much at the mo! :(
lol
Title: Re: MPG - How accurate is computer??
Post by: stealthwolf on 03 April 2009, 21:41
How do you reset the average mpg reading?

Use the button on the bottom of the right stalk (not the toggle button). Keep it pressed for more than a second and it'll reset. If you don't press it for long enough, it'll switch to the second average mpg reading (which I believe is the life mpg reading).
Title: Re: MPG - How accurate is computer??
Post by: ifti on 03 April 2009, 22:03
I have a MFSW - so I would press the down button on that for a few seconds?
Title: Re: MPG - How accurate is computer??
Post by: DJGTi on 04 April 2009, 19:14
I give the button under the stalk a quick press to put it into 'memory 2' position, and hold the button to reset. I do this when I fill up and this gives me an average speed and mpg for each tank. Not got MFSW, but think that one of the buttons does do the same as the reset on the stalk.

The instant mpg is pretty useless. Its easy to get 99.9mpg by just backing off or coasting downhill.
Title: Re: MPG - How accurate is computer??
Post by: pitch3110 on 04 April 2009, 19:52
I would think the button under the stalk should od the biz...

My A4 DIS is a mile out....The car averages 43-48mpg whne checked between fill ups but DIS shows as much as 50+.
The tech's at Audi tell me this is with tollerence. T#**ers.

I haven't check'd the ED30 yet, but off up to York next weekend to see big son at Uni & can't decide to take my 2.0TDI S-Line A4 or the wifes ED30 :undecided:
Perhaps a few hundred  :evil:in the ED30 would be good to check MPG

ta
Title: Re: MPG - How accurate is computer??
Post by: ifti on 04 April 2009, 20:23
Im pretty sure my ED30 resets the average mpg after the car has been switched off for a certain amount of time - not sure what time length it is - but it seems to reset with every trip I make......pretty much how I would like it TBH.
Title: Re: MPG - How accurate is computer??
Post by: DJGTi on 05 April 2009, 13:07
Im pretty sure my ED30 resets the average mpg after the car has been switched off for a certain amount of time - not sure what time length it is - but it seems to reset with every trip I make......pretty much how I would like it TBH.

You have 2 memories. No 1 resets after 2 hours of non driving, No 2 only resets when you do it. To switch between the two, flick onto average mpg or average speed and press the little button under the wiper stalk. Hold this button down to reset either memory. (Its all in the manual!)
Title: Re: MPG - How accurate is computer??
Post by: Teutonic_Tamer on 07 April 2009, 18:28
I've found 'miles remaining' or 'range' to be dependent on your last average mpg reading, so if your average mpg was 20, your 'range' on a full tank will be lower than if your mpg was 40.

Not quite correct.  The 'miles remaining' constantly recalculates, but displays (in multiples of 5 miles) based ONLY on your last driving habits.  So if you cane the car, the miles remaining will drop considerably - but then if you start to drive it really carefully, you can actually see the miles remaining increase, even without adding any fuel to the tank.

I've found the range to vary from as low as 300 miles to as high as 375 miles (and then stay at that reading for 25 miles because I've been cautious).

You hit the nail on the head.  When you get really low on fuel, you generally start to drive like a granny whilst trying to find or reach your local V-Power/Tesco 99 stockist, thus being economical.  Then when you fill the tank, becuause you were last driving economically, the miles remaining can initially be artificially high - but when normal driving <wink> resumes, the miles remaining drops down quite rapidly.

BTW, Stealth, did you manage to get a Haynes manual?
Title: Re: MPG - How accurate is computer??
Post by: Teutonic_Tamer on 07 April 2009, 18:36
I had the one that reads while you drive show 99mpg  :laugh:

Yup, and some makes of car can read 999 mpg.

The average is accurate,

I personally havn't checked mine, but they are supposed to be within 10% accurate.  However, if anyone does want it to be more accurate, then there is a setting the stealer (or vag-com) can tweak to adjust the accuracy of the MFD mpg readout.

dont believe the 'while you drive' one  :wink:

Sorry, but disagree.  The 'while you drive' reading is an instantaneous readout, rather than an average.  And it is very good in helping to drive in an economical manner, just like the old-skool vaccum gauges.

Furthermore, it also helps to show the efficiency gains from the FSI fuel system - comparing my B6 S4 (4.2 litre V8) against my current B7 RS4 (essentially the same 4.2 V8 as the S4, but with FSI) - the v-max fuel readings are noticeably improved on the FSI.  See my sig.  :wink:
Title: Re: MPG - How accurate is computer??
Post by: Teutonic_Tamer on 07 April 2009, 18:41
How do you reset the average mpg reading?

Don't forget - on the highline, there are two separate 'trip computers'.  Trip 1 simply clears all stored data after two hours from removal of ignition key - so is best used as a 'journey-specific' trip comp.  Trip 2 never clears, UNLESS you either clear it manually, or disconect the battery.

So for calculating tank-to-tank fuel consumption, then Trip 2 is the only one to use (brim the tank, reset your trip odometer, and ALSO reset Trip 2 - then when you next brim your tank, note the readings from the odo and Trip 2, reset then again, and use the old-skool abacus calculations from the actual quantity of fuel pumped into the tank).
Title: Re: MPG - How accurate is computer??
Post by: flyingzard on 08 April 2009, 08:35
I am pleasantly surprised with my mpg - 33 mpg over 3000 miles (from new)  :cool:
Title: Re: MPG - How accurate is computer??
Post by: ifti on 08 April 2009, 10:18
How do you reset the average mpg reading?

Don't forget - on the highline, there are two separate 'trip computers'.  Trip 1 simply clears all stored data after two hours from removal of ignition key - so is best used as a 'journey-specific' trip comp.  Trip 2 never clears, UNLESS you either clear it manually, or disconect the battery.

So for calculating tank-to-tank fuel consumption, then Trip 2 is the only one to use (brim the tank, reset your trip odometer, and ALSO reset Trip 2 - then when you next brim your tank, note the readings from the odo and Trip 2, reset then again, and use the old-skool abacus calculations from the actual quantity of fuel pumped into the tank).

Cheers T_T.
Yeh I reset Trip 2 every time I fill up - I guess its habit since I used to do it with my old car as well.
Title: Re: MPG - How accurate is computer??
Post by: Rhyso on 08 April 2009, 10:55
does your Trip 2 computer not reset it self after 99 hours and 59 minutes of driving then like in the MKIV?
Title: Re: MPG - How accurate is computer??
Post by: smartypants on 08 April 2009, 10:57
does your Trip 2 computer not reset it self after 99 hours and 59 minutes of driving then like in the MKIV?

Yes it does
Title: Re: MPG - How accurate is computer??
Post by: Rhyso on 08 April 2009, 10:59
Trip 2 never clears, UNLESS you either clear it manually, or disconect the battery.

does your Trip 2 computer not reset it self after 99 hours and 59 minutes of driving then like in the MKIV?

Yes it does

so Mr T_T is WRONG!!!  :shocked: :shocked: :tongue: :grin: :grin:
Title: Re: MPG - How accurate is computer??
Post by: smartypants on 08 April 2009, 11:14
Quote

so Mr T_T is WRONG!!!  :shocked: :shocked: :tongue: :grin: :grin:


Well I have only had my car for 2 days, but I have read the manual and thats what it tells me  :rolleyes:
Title: Re: MPG - How accurate is computer??
Post by: ifti on 08 April 2009, 11:30
The Trip 2 computer does not reset itself.
I reset it myself last week on Thursday, when I filled up my tank, and its still going up.

Its only the Trip1 computer in the highline display that resets after 2 hours to show your total journey.
Trip 2 must be reset manually - just like in any other cars.
Title: Re: MPG - How accurate is computer??
Post by: Rhyso on 08 April 2009, 11:34
The Trip 2 computer does not reset itself.
I reset it myself last week on Thursday, when I filled up my tank, and its still going up.

Its only the Trip1 computer in the highline display that resets after 2 hours to show your total journey.
Trip 2 must be reset manually - just like in any other cars.

Trip 2 in my MKIV resets after 99 hours and 59 minutes of driving - i was just curious to know if this was the case for the MKV
Title: Re: MPG - How accurate is computer??
Post by: Jkctr on 08 April 2009, 11:35
Think i have only driven it for about 15 hours since i bought it all together  :laugh:
Title: Re: MPG - How accurate is computer??
Post by: smartypants on 08 April 2009, 11:43
The Trip 2 computer does not reset itself.
I reset it myself last week on Thursday, when I filled up my tank, and its still going up.

Its only the Trip1 computer in the highline display that resets after 2 hours to show your total journey.
Trip 2 must be reset manually - just like in any other cars.

Trip 2 in my MKIV resets after 99 hours and 59 minutes of driving - i was just curious to know if this was the case for the MKV

The manual clearly states that it will reset after 99hours 59 mins OR 9999 miles OR 999 litres of fuel consumed. I've just looked at my Trip 2, its on 99hr 50 mins!

I will report back after my trip home to see if it resets itself :D
Title: Re: MPG - How accurate is computer??
Post by: ifti on 08 April 2009, 14:32
Oh, sorry I thought you meant 99 hours - not 99 hours of actual driving!
Title: Re: MPG - How accurate is computer??
Post by: smartypants on 08 April 2009, 16:13
No it IS 99 hours of actual driving!

Edit: Oh I think thats what you mean.... sorry getting confused now :)
Title: Re: MPG - How accurate is computer??
Post by: Teutonic_Tamer on 08 April 2009, 18:53
Trip 2 never clears, UNLESS you either clear it manually, or disconect the battery.

does your Trip 2 computer not reset it self after 99 hours and 59 minutes of driving then like in the MKIV?

Yes it does

so Mr T_T is WRONG!!!  :shocked: :shocked: :tongue: :grin: :grin:

<cough, cough>

Meeeeeee . . . . wrong, never!  :shocked:  :grin:  :grin:

Erm, just because Trip 2 runs out of fingers and toes at 99 hours and 59 minutes - that doesn't mean it resets.  The time just cycles round to zero again.  And the miles are the same - at 9999 miles, one more and it goes back to zero.

H O W E V E R
.
.
.
.
.
.
.
Just because the the elapsed time and total distance cycle back to zero, it still don't mean the Trip 2 has "reset".  Because the average speed and average fuel consumption will still be active!  :tongue:

<sticks out tongue, puts thumbs in ears, waves hands, and makes silly school-boy noises>
Title: Re: MPG - How accurate is computer??
Post by: stealthwolf on 08 April 2009, 20:16
I've found 'miles remaining' or 'range' to be dependent on your last average mpg reading, so if your average mpg was 20, your 'range' on a full tank will be lower than if your mpg was 40.

Not quite correct.  The 'miles remaining' constantly recalculates, but displays (in multiples of 5 miles) based ONLY on your last driving habits.  So if you cane the car, the miles remaining will drop considerably - but then if you start to drive it really carefully, you can actually see the miles remaining increase, even without adding any fuel to the tank.
That's what I was trying to get at - your average mpg would have been an indicator of your driving style, which would affect the range displayed.
BTW, Stealth, did you manage to get a Haynes manual?
Went down to halfords the weekend after your PM and couldn't spot it there. Will have another look tomorrow. Thanks for reminding me!

I had the one that reads while you drive show 99mpg  :laugh:

Yup, and some makes of car can read 999 mpg.
The highest I've made mine read was 234mpg.
The average is accurate,
I personally havn't checked mine, but they are supposed to be within 10% accurate.  However, if anyone does want it to be more accurate, then there is a setting the stealer (or vag-com) can tweak to adjust the accuracy of the MFD mpg readout.
So why isn't it already set to the tightest accuracy?

Sorry, but disagree.  The 'while you drive' reading is an instantaneous readout, rather than an average.  And it is very good in helping to drive in an economical manner, just like the old-skool vaccum gauges.
As T_T has stated, the current mpg reading (as opposed to the average mpg) is great for trying to drive economically. Quite amusing to see the effects of road gradient on mpg when you stick it 6th gear and leave it on cruise control at 60mph. I knew it had an effect but didn't know how the extent until I did this.
Title: Re: MPG - How accurate is computer??
Post by: ub7rm on 08 April 2009, 20:20

 Quite amusing to see the effects of road gradient on mpg when you stick it 6th gear and leave it on cruise control at 60mph. I knew it had an effect but didn't know how the extent until I did this.

Indeed, my journey to work is on average an incline and there is about a 3mpg difference between going to work and coming home (downhill).
Title: Re: MPG - How accurate is computer??
Post by: Rhyso on 08 April 2009, 21:19
Trip 2 never clears, UNLESS you either clear it manually, or disconect the battery.

does your Trip 2 computer not reset it self after 99 hours and 59 minutes of driving then like in the MKIV?

Yes it does

so Mr T_T is WRONG!!!  :shocked: :shocked: :tongue: :grin: :grin:

<cough, cough>

Meeeeeee . . . . wrong, never!  :shocked:  :grin:  :grin:

Erm, just because Trip 2 runs out of fingers and toes at 99 hours and 59 minutes - that doesn't mean it resets.  The time just cycles round to zero again.  And the miles are the same - at 9999 miles, one more and it goes back to zero.

H O W E V E R
.
.
.
.
.
.
.
Just because the the elapsed time and total distance cycle back to zero, it still don't mean the Trip 2 has "reset".  Because the average speed and average fuel consumption will still be active!  :tongue:

<sticks out tongue, puts thumbs in ears, waves hands, and makes silly school-boy noises>

well it must be different from the MKIV then as the average fuel consumption and average speed also resets along with the time driven and miles covered  :tongue:
Title: Re: MPG - How accurate is computer??
Post by: ifti on 08 April 2009, 22:02

 Quite amusing to see the effects of road gradient on mpg when you stick it 6th gear and leave it on cruise control at 60mph. I knew it had an effect but didn't know how the extent until I did this.

Indeed, my journey to work is on average an incline and there is about a 3mpg difference between going to work and coming home (downhill).

I have exactly the same scenario myself! lol
Title: Re: MPG - How accurate is computer??
Post by: smartypants on 08 April 2009, 22:05
Trip 2 never clears, UNLESS you either clear it manually, or disconect the battery.

does your Trip 2 computer not reset it self after 99 hours and 59 minutes of driving then like in the MKIV?

Yes it does

so Mr T_T is WRONG!!!  :shocked: :shocked: :tongue: :grin: :grin:

<cough, cough>

Meeeeeee . . . . wrong, never!  :shocked:  :grin:  :grin:

Erm, just because Trip 2 runs out of fingers and toes at 99 hours and 59 minutes - that doesn't mean it resets.  The time just cycles round to zero again.  And the miles are the same - at 9999 miles, one more and it goes back to zero.

H O W E V E R
.
.
.
.
.
.
.
Just because the the elapsed time and total distance cycle back to zero, it still don't mean the Trip 2 has "reset".  Because the average speed and average fuel consumption will still be active!  :tongue:

<sticks out tongue, puts thumbs in ears, waves hands, and makes silly school-boy noises>

I'm sorry to say, that as I said earlier my trip 2 was at 99hr 51min - I watched it tick over and the whole memory reset - everything went to Zero... Mpg, mileage, time etc.

Just as the manual said :)
Title: Re: MPG - How accurate is computer??
Post by: smartypants on 08 April 2009, 22:06
well it must be different from the MKIV then as the average fuel consumption and average speed also resets along with the time driven and miles covered  :tongue:

Nope, to hammer the point home - you are right... I watched it with my very eyes :D
Title: Re: MPG - How accurate is computer??
Post by: Rhyso on 09 April 2009, 07:54
well it must be different from the MKIV then as the average fuel consumption and average speed also resets along with the time driven and miles covered  :tongue:

Nope, to hammer the point home - you are right... I watched it with my very eyes :D

 :smug: :smug: :smug: :laugh: :laugh: :laugh:
Title: Re: MPG - How accurate is computer??
Post by: Teutonic_Tamer on 10 April 2009, 11:40
BTW, Stealth, did you manage to get a Haynes manual?
Went down to halfords the weekend after your PM and couldn't spot it there. Will have another look tomorrow. Thanks for reminding me!

Have a look on Amazon - prolly much cheaper than Halfrauds too.  Or try one of the A1 motor accessories shops, they are always cheaper than Halfrauds - might not have it in stock, but could order it in for you.

I had the one that reads while you drive show 99mpg  :laugh:

Yup, and some makes of car can read 999 mpg.
The highest I've made mine read was 234mpg.

Not trying hard enough then!  :lipsrsealed:  :grin:

The average is accurate,
I personally havn't checked mine, but they are supposed to be within 10% accurate.  However, if anyone does want it to be more accurate, then there is a setting the stealer (or vag-com) can tweak to adjust the accuracy of the MFD mpg readout.
So why isn't it already set to the tightest accuracy?

Manufacturer tollerances and mass-production.  Just like a speedometer is not 100% accurate.  A GPS speedo is much better than the standard one - and if you have the factory fit sat nav, you can get it to display the GPS mph.

Sorry, but disagree.  The 'while you drive' reading is an instantaneous readout, rather than an average.  And it is very good in helping to drive in an economical manner, just like the old-skool vaccum gauges.
As T_T has stated, the current mpg reading (as opposed to the average mpg) is great for trying to drive economically. Quite amusing to see the effects of road gradient on mpg when you stick it 6th gear and leave it on cruise control at 60mph. I knew it had an effect but didn't know how the extent until I did this.

Don't do it for too long, as it turns you into an obsessive nerd though!  :embarassed:
Title: Re: MPG - How accurate is computer??
Post by: Teutonic_Tamer on 10 April 2009, 11:42
Trip 2 never clears, UNLESS you either clear it manually, or disconect the battery.

does your Trip 2 computer not reset it self after 99 hours and 59 minutes of driving then like in the MKIV?

Yes it does

so Mr T_T is WRONG!!!  :shocked: :shocked: :tongue: :grin: :grin:

<cough, cough>

Meeeeeee . . . . wrong, never!  :shocked:  :grin:  :grin:

Erm, just because Trip 2 runs out of fingers and toes at 99 hours and 59 minutes - that doesn't mean it resets.  The time just cycles round to zero again.  And the miles are the same - at 9999 miles, one more and it goes back to zero.

H O W E V E R
.
.
.
.
.
.
.
Just because the the elapsed time and total distance cycle back to zero, it still don't mean the Trip 2 has "reset".  Because the average speed and average fuel consumption will still be active!  :tongue:

<sticks out tongue, puts thumbs in ears, waves hands, and makes silly school-boy noises>

well it must be different from the MKIV then as the average fuel consumption and average speed also resets along with the time driven and miles covered  :tongue:

Well maybe I AM wrong then - just don't get too carried away though - I won't let it happen often!  :evil:  :evil:  :evil:  :evil:  Anyhow, the book doesn't specifically state that the averages also reset too, which is why I interpreted it like I did!  :tongue:
Title: Re: MPG - How accurate is computer??
Post by: Teutonic_Tamer on 10 April 2009, 11:45
Trip 2 never clears, UNLESS you either clear it manually, or disconect the battery.

does your Trip 2 computer not reset it self after 99 hours and 59 minutes of driving then like in the MKIV?

Yes it does

so Mr T_T is WRONG!!!  :shocked: :shocked: :tongue: :grin: :grin:

<cough, cough>

Meeeeeee . . . . wrong, never!  :shocked:  :grin:  :grin:

Erm, just because Trip 2 runs out of fingers and toes at 99 hours and 59 minutes - that doesn't mean it resets.  The time just cycles round to zero again.  And the miles are the same - at 9999 miles, one more and it goes back to zero.

H O W E V E R
.
.
.
.
.
.
.
Just because the the elapsed time and total distance cycle back to zero, it still don't mean the Trip 2 has "reset".  Because the average speed and average fuel consumption will still be active!  :tongue:

<sticks out tongue, puts thumbs in ears, waves hands, and makes silly school-boy noises>

I'm sorry to say, that as I said earlier my trip 2 was at 99hr 51min - I watched it tick over and the whole memory reset - everything went to Zero... Mpg, mileage, time etc.

Bugger, you well and truly got me on that one then - what a home goal!  :embarassed:

Just as the manual said :)

Score draw.  The book makes no mention of the average figures.  It only states the total miles and the total time cycle round to zero!  :tongue:
Title: Re: MPG - How accurate is computer??
Post by: Teutonic_Tamer on 10 April 2009, 11:46
well it must be different from the MKIV then as the average fuel consumption and average speed also resets along with the time driven and miles covered  :tongue:

Nope, to hammer the point home - you are right... I watched it with my very eyes :D

 :smug: :smug: :smug: :laugh: :laugh: :laugh:

Go on, enjoy your gloating - but just don't get used to it!  :evil:  :evil:
Title: Re: MPG - How accurate is computer??
Post by: Rhyso on 10 April 2009, 11:47
well it must be different from the MKIV then as the average fuel consumption and average speed also resets along with the time driven and miles covered  :tongue:

Nope, to hammer the point home - you are right... I watched it with my very eyes :D

 :smug: :smug: :smug: :laugh: :laugh: :laugh:

Go on, enjoy your gloating - but just don't get used to it!  :evil:  :evil:

 :tongue:

going to enjoy this moment for quite a while  :tongue: :smug: :laugh: :laugh: :laugh: :wink:
Title: Re: MPG - How accurate is computer??
Post by: Teutonic_Tamer on 10 April 2009, 13:10
well it must be different from the MKIV then as the average fuel consumption and average speed also resets along with the time driven and miles covered  :tongue:

Nope, to hammer the point home - you are right... I watched it with my very eyes :D

 :smug: :smug: :smug: :laugh: :laugh: :laugh:

Go on, enjoy your gloating - but just don't get used to it!  :evil:  :evil:

 :tongue:

going to enjoy this moment for quite a while  :tongue: :smug: :laugh: :laugh: :laugh: :wink:

Keep milking it - you know another opportunity like this wont happen any time soon!  :laugh:  :laugh: