Fuel consumption. CDT to CDTi

[clf]

Originally Posted by Coups

Is adding 20% the way to 'correct' the ipk display? I see it being mentioned earlier in the thread but no explanation as to how to do it.


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I mentioned 20% but it was simply a mental calculation. I have found over the past couple of years brim to brim, that the IPK under reads the mpg by between 18 and 23%. I use the 20% as a guide. I have never been bothered to reprogram the IPK, simply because as Colin says, it would be easy to fool as you drive, and the correction seems to change.

I do find however the remain, whilst again only a guide based on recent driving, is more effective. So as I drive along, and as long as the mileage driven and mileage remain, add up to between 430 - 480, I know the mpg is relatively consistent. (Although after the longish run I had this morning, those figures are adding up to 530)

[Ray L]

Contributor A Clean Sheet is quite right, depends a lot on the individual car, also of course on its maintenance and the way its driven.

My cdti auto does 45 mpg average, but on a motorway above 50 mpg at say a steady near 70 mph.

[MustBeGettingOld]

Last week my totally unmaintained 160bhp manual tourer did 455miles of pure motorway driving, half following trucks, half 70-ish (80 on speedo), none on cruise control. It used 39.76lt which is 11.44 miles/lt (a much more sensible measurement) or 52mpg. For a heavy old bus with nearly 200k on it, that'll do me. I'm pretty sure that cruise control will take 5% off this, you can feel little surges every so often.

[Coups]

Originally Posted by clf

I mentioned 20% but it was simply a mental calculation. I have found over the past couple of years brim to brim, that the IPK under reads the mpg by between 18 and 23%. I use the 20% as a guide. I have never been bothered to reprogram the IPK, simply because as Colin says, it would be easy to fool as you drive, and the correction seems to change.



I do find however the remain, whilst again only a guide based on recent driving, is more effective. So as I drive along, and as long as the mileage driven and mileage remain, add up to between 430 - 480, I know the mpg is relatively consistent. (Although after the longish run I had this morning, those figures are adding up to 530)

Thank you for that. I knew the ipk was a 'best guess' but if it under reads by that amount I'm delighted! Mine displays just under 43mpg and although I've never done a 'brim to brim' I always reset the odometer. I always fill up at around the 1/4 mark on the fuel gauge which corresponds with around 500 miles on the odo. I don't know what that equates too but it's a heck of a lot better than my ZT 180 with the auto box that it replaced!


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[clf]

Originally Posted by Coups

Thank you for that. I knew the ipk was a 'best guess' but if it under reads by that amount I'm delighted! Mine displays just under 43mpg and although I've never done a 'brim to brim' I always reset the odometer. I always fill up at around the 1/4 mark on the fuel gauge which corresponds with around 500 miles on the odo. I don't know what that equates too but it's a heck of a lot better than my ZT 180 with the auto box that it replaced!


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I should stress, that MY IPK under reads. Yours may be different (sorry). I have read that some people's over read, some are accurate.

[Swordy]

I evidently need a new thermostat from comments on a previous thread .
Which kit would you recommend??
Seems a big price difference.
Thanks
Paul

Originally Posted by good_mojo

in addition to this sound advice, check that your car is getting up to temperature. If the temp gauge is not reaching quarter to, your thermostat has failed. You can fit a Renault 5 stat in the front hose rather than mess on with the awkward placement of the original. (Leave the old one in because it fails in the open position).

Proper temperature makes a heck of a difference to the efficiency of our diesels and if the stat has failed, fitting a new one will improve your mpg a lot.

[grivas]

Originally Posted by good_mojo

in addition to this sound advice, check that your car is getting up to temperature. If the temp gauge is not reaching quarter to, your thermostat has failed. You can fit a Renault 5 stat in the front hose rather than mess on with the awkward placement of the original. (Leave the old one in because it fails in the open position).

Proper temperature makes a heck of a difference to the efficiency of our diesels and if the stat has failed, fitting a new one will improve your mpg a lot.

The temperature gauge is largely cosmetic

[andymc]

Originally Posted by Swordy

I evidently need a new thermostat from comments on a previous thread .
Which kit would you recommend??
Seems a big price difference.
Thanks
Paul

I got my inline thermostat from DMGRS, trader on here. Can't remember the price but it's low, maybe six quid or thereabouts. Does the job I need it to - brought operating temperature up from 78-79 degrees to 86-88. Much less of a job to jit as well, by all accounts (I had mine fitted for me but the bill wasn't steep).