Mk8 460 minibus fuel consumption

[johnporter11]

The last five tankfulls have ranged from 26.3 to 29.9mpg. The last one on a mix of very good A-roads and some motorways ranging from 55 to 70mph (the speed restrictor has been lifted due to it now being registered as a 3500kg PLG! van with windows - campervan if you like).
However, the computer mpg on the last outing was 34.5! Hence why I always calculate it manually from tank to tank fills.
I know it's a bit of a beast, but it's currently weighing (with driver, passenger and Beagle dog) 3550kg. I know, I need to trim a little fat to be completely legal. But this is just 250kg over the previous unladen weight. I'm not forcing it. I'm trying to drive as economically as possible but not hamper the traffic flow.
Does anyone think sub 30mpg is OK for these things?

[dumper]

Mine run at 32 mpg on a run to Holyhead port fully loaded on a fishing trip to Ireland over the last 7 trips that was running at 58 mpg with the 3.1 diff normally I would run at 53 but with it been so high geared and not in a rush I used run faster to not slog the engine and end up changing gear all the time .
I have since had the crownwheel and pinion changed to a3.73 this weekend I’ve been to Anglesey race circuit about 3500 kgs gvw for two rally’s running at 53 mph 50 by the satnav it’s given 38 .6 on a 185 miles running round the circuit for two days and a run home at 60 with some burst of 70 overtaking and some crawling on motorway holdups it has dropped to 31.9 .Mine is a 2.2 125 remapped by vantuner to 155 ish all the figures are off the computer so will drop a bit if worked out on paper.
In winter it’s between 27 and 29.7 on winter diesel.

[johnporter11]

Thanks Dumper. Mine is a 155ps as standard. But I don't know the diff ratio.
There's a lot of info in you post and I'm still trying to assimilate it.
When you said "last 7 trips that was running at 58 mpg with the 3.1 diff" did you mean 58mph? Cos I don't know of a big Transit that does 58mpg!

Am I right in saying that because you've changed from a 3.1 diff to a 3.7 you've lowered the final drive gearing? More engine revolutions per axle revolutions.
And this has changed your speedo reading because of that? 53mph versus 50 satnav.

[dumper]

Sorry I ment mph not mpg the speedo on modern vehicles usually reads 3 miles slow so 53 on speedo is actually 50 mph .
With the 3.1 diff the engine revs at 50 mph was 1600 rpm ish so I used to run at 58 mph on duel carriageways otherwise I was always changing gear and on single carriageways I very really used 6 th gear .
Yes the engine is now revving higher with the 3.7 the 50 to 60 mph rev range is 2000 to 2400 rpm now I can use 6 th gear all the time comeing home from Holyhead the big hill on the A 55 it actually increase speed going up the hill starting at 60 at the bottom it will be doing 70 when I got to the top but with the 3.1 I used to start 70 at the bottom and have to change down to 5 th near the top it used to be the same on windy hill on the M 62 and with me doing a lot of off road driving it’s also much better for that as well.

[johnporter11]

Yes I agree with that. I haven't seen a torque curve for this engine. As I said, mine is the 155ps version. But torque is everything when it comes to a big hill.

[dumper]

Yes I agree with that. I haven't seen a torque curve for this engine. As I said, mine is the 155ps version. But torque is everything when it comes to a big hill.

Very true you need more torque on modern vehicles as ever thing now is over geared I’m not sure but I think it’s something to do with emissions cruising at a certain speed probably ok on a rolling road but no good in the real world you just end up changing gear all the time or running in a lower gear .
Just like quoted mpg figures are always over optimistic .

[JamesHow]

How much do you guys get out of a tank on the trip computer? I get approx 550miles... I know it's not scientific but I done alot if town driving too which would ruin a mpg calc.

Cheers James

[johnporter11]

A 61 litre fill gave me 400 miles. Not sure how much it exactly holds.

[dumper]

A 61 litre fill gave me 400 miles. Not sure how much it exactly holds.

Not really sure I never let it get less then a1/4 and fill it at about a1/3 of a tank as the night heater cuts out at not much over a 1/4 .

[Essexaviator]

Hi I’m running a mark 8 with 1300 miles on clock 185bhp manual and getting average of 43 mpg - just got 50.2 mpg on a run last week and wasn’t trying to be economical so that’s how mines running. I do use premium diesel.


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[dumper]

That’s good but with it been a custom I’d expect that with it being a lot smaller then a460 H3L4?.

[johnporter11]

A 460 H3L4 weighing three and a half tons and a big frontal area....
Those figures look crazy good though. But you still have to do a manual calculation to get the true figure though. The computer on mine is nearly 5mpg optimistic! A bit like manufacturers' figures. They should be held to task like the emissions claims....