613 miles on diesel P38 - can you do better?

Speedex750 · Jan 30, 2012

Evening all,

Just filled up, 86.75 litres cap to cap with 613 miles driven on a diesel P38A. About 500 motorway miles and the rest around town. A bit close to the bottom of the tank, the last 30 miles were done with the warning light on, RAVE says 90 litres capacity. About 32mpg according to my O level sums, with 28mpg on the dash display. I'm pretty chipper on that.

But can it be bettered, what are you achieving - and how?

Clarky130 · Jan 30, 2012

I'm getting 29 mpg average, with mostly country road driving. Seeing 32mpg average on a long run. Not bad for a 2.7 ton beastie!

jt_armstrong · Jan 30, 2012

Best I ever got was 406 miles on a tank. Mind you the tank is bigger and was full of proper fuel

Goodfella · Jan 30, 2012

well thats only marginally better than i get on average on LPG. Your £123 ish quid of diesel would get me 2.5 tanks of lpg plus the V8 grunt. :fencing::amen:

Golan · Jan 31, 2012

Oh dear I can see this turning into another petrol diesel battle...... :boxing:
I've got a little App. on my phone that tells me my overall average is around 26 mpg and getting better, I tow a trailer quiet a bit and do lots of short trips.
I've got an airport trip this week so I'll reset the clock and see how much I can squeeze out of the tank.....

dave4x4 · Jan 31, 2012

613 miles on a tank full is very good.

I am averaging about 26 or 27 mpg over the month burning 50/50% mixture of SVO and diesel.

fortgrange · Jan 31, 2012

I managed a non stop 850 mile trip through Spain in the summer in my Classic.

Mind you that was using about 90 litres of unleaded and 130 litres of LPG

Clarky130 · Jan 31, 2012

dave4x4 said:
613 miles on a tank full is very good.

I am averaging about 26 or 27 mpg over the month burning 50/50% mixture of SVO and diesel.

Where does one get SVO? And can it be used in the 2.5DSE without mods?

dave4x4 · Jan 31, 2012

Rapeseed oil from Costco in 20L drums. Costs £1 / L. Not a huge saving but it slowly adds up.
50/50% mix there is absolutely no problem on a DSE. You can increase this in the summer. The DSE is very happy to run on veg oil. One of the advantages of indirect injection and a Bosch FIP.
From an empty tank I fill it with about 40L diesel, drive home, then put in 40L veg oil using a proper dispensing pump I bought. It seems to mix OK in the tank. It gets sloshed around when driving. Engine actually sounds better - less of a diesel "ping".
If you do it, keep records in the car. You are allowed to use 2500L a year.

Clarky130 · Jan 31, 2012

Not much of a saving then - especially if (as I have read elsewhere) you need to do more frequent oil and fuel filter changes? Is that true?

seanmull · Jan 31, 2012

600 miles on one tank

mine wouldnt do it on a trailer ----

davef2901 · Jan 31, 2012

Hmm, on a motorway run, I get about 36mpg equivalent on lpg in my jap spec 4.6 autobiography, mind you it gets 26mpg on petrol then, it's a lot worse round the doors. I average about 29-30 in general driving and I'm happy at that (lpg @67.9ppl round here). I keep a bloody close eye on coolant use mind-I've been warned about dropped liners on v8 lpg motors. You pays your money and takes your choice. I've a mate with a 2001dt that has averaged 29.9mpg since it was new so I believe your figure

dave4x4 · Jan 31, 2012

Fuel and oil changes are presently as per normal service (6000 miles). I've not had any problems and I don't expect any using SVO. However if I used WVO it may be a different story.
Using WVO obviously gives the biggest savings when it is free, but every man and his dog wants it now and usually you have got to pay for it. It is also a lot of hassle.

Speedex750 · Jan 31, 2012

Thanks for the replies including the humorous ones!

Where I was hoping this thread would go is what else I could do simply to edge a few more mpg's?

Things I've done so far;
Goodyear Wranglers tyres (18") with good tread running at 38psi all round and good alignment
5/30 fully synthetic engine oil
Clean air filter
Magnets on FIP inlet and rack pipes (yes, I'm 'gadget' adverse as well but for what they cost I thought why not)
Tried Shell Optimax - no noticable improvement, using supermarkets now where I can get Nectar points and Morisons £5 vouchers
Try to accelerate smoothly up to 50mph when top locks in and then cruise control 60-65mph just above 2000rpm where maximum torque is generated but not too fast where the 'aerodynamics of a brick' cut in
Anticipating the traffic and avoiding getting boxed behind slower vehicles; overtaking when its OK but without having to accelerate
I've got some fully synthetic axle oil to put in when the weather picks up a bit (don't know what's in there)

I haven't got a chip so I'm interested if the claims for improved mpg's are bourne out in practice, I would like to avoid the kick downs that happen on even modest motorway inclines. And that's always where the trucks pull out to overtake! Doing less than 60 and getting below 2000rpm seems to make this more likely.

I'm sure some of you aren't fussed about mpg's, you enjoy your P38 for other reasons. I agree with the later because of the many comfortable, safe miles I'm covering - but doing that economically helps fund all the bits and pieces that a DHSE consumes!!

Thanks for your input.

bigsmellydaddy · Jan 31, 2012

Hi.

I have had my truck a couple of weeks and am glad to say it is indicating 31-ish average which looks about right on the fuel gauge. This is local stuff without to heavy a foot. It is chipped, which I was told was to make it a bit less slow ! Well happy with the economy, not so happy that it drained the battery in 2 dsays because of a wi-fi router !:doh:

DTL

Davie F · Jan 31, 2012

Only way I would get that is if I put up a bloody sail, my DT averages 24.6mpg.
Davie :biggrin1:

tommo1972 · Jan 31, 2012

I must be doing something wrong! best Ive got out of mine so far is 22mpg on normal around town.

jerrytlr · Feb 1, 2012

Mine averaging around 25mpg, no way I could get it up to 30 :-(

Cheers,

Jerry

Datatek · Feb 1, 2012

bigsmellydaddy said:
Hi.

I have had my truck a couple of weeks and am glad to say it is indicating 31-ish average which looks about right on the fuel gauge. This is local stuff without to heavy a foot. It is chipped, which I was told was to make it a bit less slow ! Well happy with the economy, not so happy that it drained the battery in 2 dsays because of a wi-fi router !:doh:

DTL

If it's chipped the fuel readings on the display are pure fantasy as the computer does not know about the extra fuel being put in by the chip.
With a PSI Power box mine used to read 28 to 32mpg which came out at 24 to 30mpg brim to brim according to useage. with the power box removed (to save the gearbox) it averages 24mpg brim to brim and up to 28mpg on the autoroute. It was slightly more economical on long runs with the powerbox fitted, I believe this was due to the fact that it would maintain speed on inclines without changing down. With the powerbox removed it downshifts at the least excuse on the motorway.

seanmull · Feb 1, 2012

im curious to know what the magnets on the fuel inlet and rack pipes do??

613 miles on diesel P38 - can you do better?

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