Why has my fuel economy improved

[solmanic]

Let me preface this thread with I'M NOT COMPLAINING, but I sure am curious...

The last two tank fulls in my Puma Defender have managed substantially greater mileage than any previous ones.

Since new the Defender has averaged 600-620km from a tank (approx 62l-65l each fill). Pretty much bang on 10l/100km or a bit over, every tank, city, highway or off-road. The vehicle has now done 27000km and the last two fill-ups have gotten 680km and 702km with 62-64l put in. This last one I ran it until the low fuel warning light came on just to check that it still worked. I thought the calibration might have gone out, but no - light came on, and the tank wasn't any emptier than before.

Now I always expected the economy to improve as the engine loosened up, but not all of a sudden. I thought the tank before last might have been an anomaly but this last one was the same. It appears I have had an overnight improvement of about 1l/100km. I haven't, to my knowledge, changed my driving style or been driving anywhere different and the vehicle has not had anything heavy taken off. Both the last fills were at the same Caltex-Woolworths service station I usually use.

Has Caltex changed their Diesel somehow?
Is my extra 8c per litre here in Queensland buying me better fuel?
Is there a magic setting in new Defenders that changes the engine tune to something more efficient at 26000km?
Is it my imagination?
Has a Holy man secretly given my Defender a blessing whilst it was parked at the shops?
Should I just shrug and say "oh well, that's Land Rovers for you" and go on my merry way?

:confused::confused::confused:

[TimNZ]

Probably just better fuel?? I've found the fuel economy improved after about the first 15000k's, its done 40000k's now. The other week I repeted a 500k(ish) trip I did when I first brought my car, it nearly used a tank the first time, (fuel light came on), but this time I had quarter of a tank left.

Tim

[JamesH]

Trying to find a negative spin on what appears to be simple good fortune happens to be specialist area of mine...

Sometimes fuel pumps can be cantankerous and click off at different levels, the guage might show full but the actual level might easily be a litre less in the filler pipe. I don't know about yours but my guage takes a while to mover while the car drinks the "extra bit".

Sure, this sort of anomally generally evens out when you do your next fill and you have already had your next fill so you would have expected a correction but maybe the pumps have been serviced (or need a service) and delivering the fuel differently. You might get your correction on the next fill?

[DeeJay]

Kinda reminds me of the film where a guy kept skiting to his neighbour, (played by Robin Williams), about his Volkswagons great economy, so Williams kept putting extra fuel in it each night until this guy got 125mpg and was going nuts trying to keep calm about it..:)

Got a locking fuel cap ??:twisted:

[Richard]

you been using BP diesel? found ive been getting better fuel economy with my defender as well using that, theres some additive they have been advertising they add to their diesel

[solmanic]

Nope. All recent fills have been at our local Woolworths Caltex.

[Mrlandyman100]

My last tank full was at BP i just worked out and maybe thats the reason why i seem to be getting better km/l. But i will find out tomorrow when i fill up again. I think i have gone about 30-40km more when at the same point on the fuel gauge.

[omvanders]

My landie-nut mechanic swears that Caltex gets him up to 10% better economy than 2 other brands in particular, one of which starts with B and the other with S. ;) I'm yet to be convinced, but am in the throes of testing his theory.

[Scallops]

I have known many people who will tell you that any engine will get it's best fuel economy from about 30000km onward - why? I don't know. Mine did this too - I went to about 9l per 100km.

[vnx205]

Kinda reminds me of the film where a guy kept skiting to his neighbour, (played by Robin Williams), about his Volkswagons great economy, so Williams kept putting extra fuel in it each night until this guy got 125mpg and was going nuts trying to keep calm about it..:)

Got a locking fuel cap ??:twisted:

That was a classic. :D

Unless your tank is a lot easier to fill than mine on my cab/chassis, it is unbelievably easy to get significant apparent fluctuations in fuel economy.

After the nozzle clicks off and froth dribbles out on the ground and the tank appears to be full, I can add another five or six litres, provided I have the patience to dribble it in very slowly.

So that means I could leave the servo with only 70 litres. That would mean that the last tankful would appear to have been about 10% better than normal and if I filled up really carefully, the next one would appear 10% worse.

So the difficulty of filling some tanks, especially with frothy diesel, can give an apparent 20% variation in economy from one tank to the next.

I tend to be a bit cynical about fuel consumption claims based on one tank or even just a few tanks full.

That doesn't mean yours isn't real or isn't accurate, but I bet the circumstance I have described is more common that dramatic changes in economy.

[pbroz]

Sorry couldn't resist... I've been doing this since new... the peaks are either off road / summer time a/c or new long range tank back in November... I like the sound of this improving some what...

My wife just watched me writing this and said I was nuts! I don't think she quite understands...

[solmanic]

... Mine did this too - I went to about 9l per 100km.

Yeah, but in the space of one tank-full?


...Unless your tank is a lot easier to fill than mine on my cab/chassis, it is unbelievably easy to get significant apparent fluctuations in fuel economy.

After the nozzle clicks off and froth dribbles out on the ground and the tank appears to be full, I can add another five or six litres, provided I have the patience to dribble it in very slowly...

I am basing my figures on the actual litres pumped into the car each time I fill up as shown on the bowser. I know what you mean about temperamental fuel fillers, and I always go a few litres beyond the click-off. Incidentally, nearly all my fills have been using the same bowser at my local servo. It's always the scum-of-the-earth-filthy-diesel bowser stuck way to buggery out beyond the covered "consumer" petrol bowser area with one regular & one high-flow nozzle and no queue. I have stopped using the high-flow nozzle since I am suspicious that it upsets my fuel gauge somehow (a couple of times it has refused to show completely full after topping off).

Anyway, a couple more fills should confirm this happy trend.

[spudboy]

...My wife just watched me writing this and said I was nuts! I don't think she quite understands...

You are not alone....

Still waiting for my economy to get down to 10L/100. Still up around 11, but I haven't hit the magic 26,000Km yet ;)

[Sleepy]

you been using BP diesel? found ive been getting better fuel economy with my defender as well using that, theres some additive they have been advertising they add to their diesel

Funny, I was going to say the opposite. I get worse on BP. (Maybe it's different in Melb.)

[abaddonxi]

You're in limp home mode.

:D:D:D





Couldn't resist.

[dullbird]

I have known many people who will tell you that any engine will get it's best fuel economy from about 30000km onward - why? I don't know. Mine did this too - I went to about 9l per 100km.

Because they reckon by then everything as loosened up in he engine....and thats why the economy gets better...
however I was told after 20,000k

I think ours is worse we get more per litre around town then we do on a long run it appears anything over 100k sucks it...oh and we use BP perhaps there is a trend:D

[frantic]

Could be the cold? The fuel shrinks and does not froth as much in the cold as compared to 25+ that you normally get in Qld so you may be getting more fuel in your tank. Also turbo's operate better in cooler weather and this could be a factor?
This does not apply south of canberra as ACT/VIC/Tassie always cold so any sensor in the computer would not register a change from cold to bloody cold.:D

[scarry]

The guy next door is a Nissan specialist,and works almost soley on Pootrols & Navara diesels (poor buggar).:eek:;)& has done for many years

He recons a diesel is not run in fully til it has done over 40k.

I have noticed with new TD5's they never got good fuel economy till they had done around 10k at least.

Dunno how fuel economy could change overnight though:confused:,particularly if you havent changed anything...

[dullbird]

The guy next door is a Nissan specialist,and works almost soley on Pootrols & Navara diesels (poor buggar).:eek:;)& has done for many years

He recons a diesel is not run in fully til it has done over 40k.

I have noticed with new TD5's they never got good fuel economy till they had done around 10k at least.


Dunno how fuel economy could change overnight though:confused:,particularly if you havent changed anything...

Deosn't does it I thought it changed over a tank of fuel:p which is usually around 2 weeks:D...unless of course your in le monz (or however you spell it:lol2:

[Pete1]

My 2008 Defender has 32000 km now and is slowly getting better economy ! I can also confirm that I get FAR BETTER economy with Caltex fuel than with any other . A mate has a new Colarado ( poor fellow ) and he gets better economy also. We both travel the same 700 km every week

[solmanic]

3rd tank since the bizarre fuel economy improvement...

650km from the last tank full (no warning light) - long highway runs (5.5 hrs) at 100km/hr+ which would usually hammer the economy down. Put in 61 litres. Caltex diesel again, but this time from a different servo.

[CapeLandy]

We just covered 6,800 km's with a fully loaded vehicle and roofrack with boxes etc and we varied between 10,4l/100 travelling mostly at 90km/h on road and 30 to 40km/h offroad and worst figure was 13,3 including soft sand and four persons.
Very impressed. Our manual states that 13l/100 as normal consumption if I remeber correctly.
We did note the combustion noise got worse the more remote we were and the dodgier the diesel. We had none of that low sulphur diesel at all.
Now that we are back on the low sulphur stuff she has gone quiet again.