D4 update - opinions and a few facts

As a result of all this recording and analysis, do the figures stack up against the trip computer? Or do they confirm that the trip computer consistently paints a rosier-than-real picture about average fuel consumption, while at the same time being a panic merchant about the need to fill up?

I usually run the bowser figure through a calculator when I fill up and check it against the average shown on the trip computer (D4 3.0 with all known updates completed). The trip computer is consistently about 10% lower than real consumption: when the trip computer gives an average of 9.1, the bowser shows actual consumption of 10l/100km; computer 10 = bowser 11.1; computer 11.1 = bowser 12.3, etc. I seldom fill up at the same place, so it's unlikely to be a fault with the bowser.

The average fuel consumption figure shown by the trip computer also never tallies with the distance to empty, which normally warns of certain death by about 700km even when the average consumption figure is showing around 9 so there should be a good 900km in the tank (or 840km once you factor in the error in the average). I tend to err on the side of safety and fill up by about 700km but I'd hate to need an accurate figure to wring maximum distance out of the tank.

This is only the 2nd car I've had with a trip computer and the other one played similar games (Peugeot 406 diesel), so perhaps all trip computers do this? Or is it just mine?

I've had the same experience Beamin.
For example, I run the D4 tank down to ~50km remaining & the trip computer saying the tank average has been 10l/100kms. So should only have 5l left in tank, therefore should take 75l to fill. Each time in takes 67-70 liters to fill.

Similar experience with Touyota Prado & Nissan Pathfinder trip computers. The Nissans was the worst w.r.t. distance to empty. I can always get 100-150kms more that it says I should!

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Originally Posted by GeorgeK

I have been using 'Road Trip' ($5.99 on iTunes) on my iPhone ...

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Anyone found any similar apps yet for Android?

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Originally Posted by eddomak

Anyone found any similar apps yet for Android?

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Ok, sorry to answer my own question - I had only searched for "fuel", "logbook","economy", but it looks like "Mileage" is the term to use.

Here are 2 apps:

• aCar - supports multiple vehicles
• Mileage - only supports 1 vehicle

Both just need the odometer reading, and any 2 of the following:

• Unit Cost
• Total Cost
• # Litres

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Originally Posted by ADMIRAL

You guys need to get out more !!

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The more you get out, the more you gotta record! ;)

Actually, it is interesting to go back over the years and see the figures... I remember the days when diesel was less than 80 cents a litre...

This prompted me to look back at some old spreadsheet records...
The oldest data I have is 20 Dec 1991 when I filled the Nissan TRX Bluebird for 57.9c/l in Brisbane. I was 22 y.o.. Ahhh the memories!

57.9? Expensive stuff what? Sadly, I remember my father filling the HD for 50c a gallon... he'd hand over $5 AND get change! Best I ever paid was in Toowoomba at 25c/l way back when.

Now to the point of this post though. As we are holidaying in Tassie, we did one of the tourist things this morning in Hobart and went up Mt Wellington. As a point of interest, I switched to the 'trip auto' for the trip computer and after getting to the bottom, a 9km trip, we had averaged 0.2l/100km. Mind you, it's a drop from 1300+/- meters, and twisty so I was in 'command shift' using 2nd/3rd to keep the speed down so it was only the moving from the car park to the initial down hill where we where having to use any fuel - I still don't believe the 0.0l/100km figure when off throttle though, it's got to put SOME fuel in to keep the thing running, surely?

And the damn 'gearbox fault' hit again. Oh well, it will be fixed when we get home along with some rattles.

Having had numerous cars with trip computers, I know their failures/characteristics.

I have no idea how accurate they are or could be...under the right circumstances...but it's a moving feast. In theory the computer 'snap-shots' at set intervals but the data that they use is affected by 'right there and now' data....were you accelerating and braking a lot...on the cruise....how heavy....load and fuel weight....speed....blah, blah, blah.

Around town I just let the computer do it's thing....which normally isn't too flash but not bad for a truck of 2.6Ts. If I'm serious about a figure I reset on the cruise and work on those figures. D4 3.0TD, fully loaded, 3 hrs drive to Inskip Point.....8.4L/100kms.

Not bad I'd say.

Regards,

Kev.

Undulating country near NSW/Qld border, on or about 100, limited cruise with the camper trailer on - around 12 by computer. Gundy/Moree and back (dead flat) on or about 100, solo, low 8's. 2000 K's on board only. Good going I reckon, particularly the towing figure.

OBT

Seems most of us can add 1 - 1.6 l/100km to the figure displayed and be roughly correct with the mileage/fill manual calculations. I'm more than happy with the economy down here in Tassie.
10.3l/100km since we left home nearly two weeks ago is fairly good I feel. 2089 km and 219l of fuel is not bad for a VERY hilly area and being unfamiliar with the roads too. With the nagging woman telling us where to navigate to, it's not uncommon to go from sea level to 700m above, and down again over 30 or 40km! I'm in love with the place and can't wait to get time to learn fly fishing, and come back!