2.5 V6 more economical than a Prius!

Space_1999 · 17th November 2008, 22:24

...at least according to my trip computer, which tells me that I'm getting about 48MPG average (including town driving)! Being the untrusting soul that I am, I suspect there might be a fault - but where? Any ideas guys?

T-Cut · 18th November 2008, 00:20

When you reset the computer, it has to start again from scratch with the data it uses to calculate average fuel consumption, average speed, etc. The accuracy of the reading it shows really depends on the number of data 'samples' it has to work with. The fewer the samples the less accurate is the result. So, if you reset the fuel consumption figure and almost immediately check the new mpg figure, it will be way out, probably a quite rediculous result. For example, 7mpg or 120 mpg - each is possible depending on driving circumstances after the reset.
To get anything like a realistic figure, you should not reset the computer at all. Only then will the result be close to the average figure over the period since the last reset. The other factor to bear in mind is accuracy. The mpg calculation is only as good as the data fed to it. This is supplied by sensors like the fuel level and wheel speed sensors, which the ECUs translate into your petrol gauge and speedo readings. None of these readings is accurate, they vary from the truth a bit and this usually leads to optimistic mph and mpg figures. They can be 'trimmed' to be more accurate using the settings available in the instrument diagnostics routines. For most people, the readings are near enough, but to get your consumption even more accurate, you have to start measuring the fuel used by filling the tank with a recorded amount using the petrol pump displays (these are very accurate in comparison).
If you leave the computer for a few weeks, the fuel consumption figure will become much more realistic and more accurate tahn the one you are seeing now.

TC

Space_1999 · 18th November 2008, 19:36

thanks for your help, but yes I'm aware of all this. It's still saying I'm averaging nearly 50MPG without a reset for 2,500 miles!

Hence my query!

Presumably I have a dicky sensor somewhere...?

Kearton · 18th November 2008, 19:59

Quote:

Originally Posted by Space_1999

thanks for your help, but yes I'm aware of all this. It's still saying I'm averaging nearly 50MPG without a reset for 2,500 miles!

Hence my query!

Presumably I have a dicky sensor somewhere...?

This is close to what Rover's sales brochures claim - 49.7 mpg combined. Perhaps it was your car they checked it on. :-)

Regards,
Kearton

Space_1999 · 18th November 2008, 23:35

well if it's true, I hope it makes all you diesel guys jealous!

rt2 · 19th November 2008, 01:27

Quote:

Originally Posted by Kearton

This is close to what Rover's sales brochures claim - 49.7 mpg combined. Perhaps it was your car they checked it on. :-)

Regards,
Kearton

My drivers handbook says 39.4 mpg max on extra urban.

I can beleive it on a couple of hundred mile run the other day 36.2 was my average.

Departed · 19th November 2008, 06:54

I'd agree your figures are suspect. I know the 2.0s are not the best, but I can't better 33MPG on a reasonable run, below 30 round town. And that's after fixing my VIS motors.

afcbadam · 19th November 2008, 22:10

i had a vw golf gti for a courtesy car. i was getting 199 mpg acording to the computer on a steady run

karl_683 · 20th November 2008, 08:04

More economical than a Prius? Mine is. At least thats what I tell myself over and over again. If I keep saying it I should eventually believe it

.

Although its nearly as economical as my old rover 214.

Tatts · 20th November 2008, 10:24

Best I've ever had is 27.26mpg, although I didn't buy a 2.5l V6 with economy in mind!

17th November 2008, 22:24	#1
Space_1999 Regular poster Rover 75 saloon Join Date: Nov 2007 Location: Marlborough Posts: 53 Thanks: 0 Thanked 0 Times in 0 Posts	2.5 V6 more economical than a Prius! ...at least according to my trip computer, which tells me that I'm getting about 48MPG average (including town driving)! Being the untrusting soul that I am, I suspect there might be a fault - but where? Any ideas guys?

19th November 2008, 22:10	#8
afcbadam Gets stuck in 2004 MG ZS 180 Join Date: May 2008 Location: Southampton Posts: 978 Thanks: 0 Thanked 0 Times in 0 Posts	i had a vw golf gti for a courtesy car. i was getting 199 mpg acording to the computer on a steady run __________________ AFC Bournemouth www.themgzs.co.uk Inner wing open cone Oil catch tank Janspeed cat back Janspeed de-cat Reidy Re-mapped

20th November 2008, 08:04	#9
karl_683 Loves to post Jaguar X-Type Join Date: Jul 2008 Location: Peterborough Posts: 323 Thanks: 0 Thanked 0 Times in 0 Posts	More economical than a Prius? Mine is. At least thats what I tell myself over and over again. If I keep saying it I should eventually believe it. Although its nearly as economical as my old rover 214. __________________ [SIGPIC][/SIGPIC] Member No. 494 - Visit my DeviantART Profile: http://karl683.deviantart.com/

20th November 2008, 10:24	#10
Tatts This is my second home MG6 TL Join Date: Nov 2006 Location: Tarn Posts: 5,269 Thanks: 2 Thanked 46 Times in 37 Posts	Best I've ever had is 27.26mpg, although I didn't buy a 2.5l V6 with economy in mind! __________________ http://www.wcgsig.com/115562.gif

18th November 2008, 00:20	#2
T-Cut This is my second home Rover75 and Mreg Corsa. Join Date: Nov 2006 Location: Sumweer onat mote o'dust (Sagin) Posts: 21,753 Thanks: 341 Thanked 3,660 Times in 2,924 Posts	When you reset the computer, it has to start again from scratch with the data it uses to calculate average fuel consumption, average speed, etc. The accuracy of the reading it shows really depends on the number of data 'samples' it has to work with. The fewer the samples the less accurate is the result. So, if you reset the fuel consumption figure and almost immediately check the new mpg figure, it will be way out, probably a quite rediculous result. For example, 7mpg or 120 mpg - each is possible depending on driving circumstances after the reset. To get anything like a realistic figure, you should not reset the computer at all. Only then will the result be close to the average figure over the period since the last reset. The other factor to bear in mind is accuracy. The mpg calculation is only as good as the data fed to it. This is supplied by sensors like the fuel level and wheel speed sensors, which the ECUs translate into your petrol gauge and speedo readings. None of these readings is accurate, they vary from the truth a bit and this usually leads to optimistic mph and mpg figures. They can be 'trimmed' to be more accurate using the settings available in the instrument diagnostics routines. For most people, the readings are near enough, but to get your consumption even more accurate, you have to start measuring the fuel used by filling the tank with a recorded amount using the petrol pump displays (these are very accurate in comparison). If you leave the computer for a few weeks, the fuel consumption figure will become much more realistic and more accurate tahn the one you are seeing now. TC

18th November 2008, 19:36	#3
Space_1999 Regular poster Rover 75 saloon Join Date: Nov 2007 Location: Marlborough Posts: 53 Thanks: 0 Thanked 0 Times in 0 Posts	thanks for your help, but yes I'm aware of all this. It's still saying I'm averaging nearly 50MPG without a reset for 2,500 miles! Hence my query! Presumably I have a dicky sensor somewhere...?

18th November 2008, 23:35	#5
Space_1999 Regular poster Rover 75 saloon Join Date: Nov 2007 Location: Marlborough Posts: 53 Thanks: 0 Thanked 0 Times in 0 Posts	well if it's true, I hope it makes all you diesel guys jealous!

19th November 2008, 06:54	#7
Departed Retired -- Join Date: Jan 2007 Location: -- Posts: 3,785 Thanks: 0 Thanked 4 Times in 4 Posts	I'd agree your figures are suspect. I know the 2.0s are not the best, but I can't better 33MPG on a reasonable run, below 30 round town. And that's after fixing my VIS motors.