Vito 3L V6 owners - what fuel consumption do you get?

[MikeyBee]

Hi everyone, newly registered here. I have a 3L Vito Dualiner which I use for work as a van, travelling around fixing central heating boilers, and my fuel consumption seems to be all over the place. I run the van part loaded with boiler spares, weighing perhaps 300kg.

I travel quite long distances. Yesterday for example I did 140 miles and at the end, the dash display was saying 27.1mpg. The day before I did 100 miles and finished the day at 25mpg. This is mainly on A class roads and the motorway. Other days I can do a similar trip and see 32 or even 34mpg. The trouble is, the poor mpg days now far outnumber the good days and I'm beginning to obsess about it, driving carefully, feathering the throttle and using the cruise control as much as possible to eke out the fuel.

The long term fuel consumption since the last reset 20,000 miles ago shows up as 29.1mpg so this seems to support my perception the fuel consumption is deteriorating. So I came here to see if I this is a common problem and there are known solutions. I've had a brief read-around of old threads and not found much discussion. Ideas seem to be a sticking brake caliper, underinflated tyres and a very interesting post by Botus which I don't quite fully understand yet. Here:

20% improvement in MPG at the touch of a button

hard to fathom but real result.... on the S class !!! Been trying to sort nasty fuelling on my bike for years.... it had the stock BMW map that was an utter joke, but easily fixed with an aftermarket bit of kit by an American company... you plug it in and it just lies to the bike about what the...

forums.mercedesclub.org.uk

My garage said straight away when I asked them, it is failing injectors as the van has done 270k miles. They recommend new injectors too as recon injectors are trouble in their experience. So what does the board think, please? And what mileage do you get from yours if you run a V6 Vito?

Many thanks for reading.

 

[Kev555]

Hi MikeyBee welcome, I would get a second opinion on recon injectors from an injector specialist to see what they recommend. I have the 4 cylinder OM651 and a manual box in my van and consistently get around 30-35 MPG on the computer on a long run. But if I'm not in 6th gear as much as possible that can drop to late 20,s. I get 27-29 MPG just running local. I dont pay much attention the long term fuel consumption reading as its usually in the low 20,s. I did have to change my injectors at 150,000 but mine are different injectors and a different engine. Take it to a Merc Indie and star diagnostics will paint a clearer picture and he will tell you if you should recon or replace the injectors if faulty. Some guys in the know on the forum here will prob have experience of best option to replace the injectors.

 

[MikeyBee]

Hi Kev, many thanks for your detailed reply.

I too had a four cylinder OM651 before this van and fuel consumption was never great, but on changing to this OM642, fuel consumption was noticeably worse. I had a long chat with another OM642 Vito owner and he said his regularly gave 30mpg (according to the dash display) on a long run but mine mostly returns 26 or 27, with the early part of the journey often showing sub-20 for the first 30 miles. The odd thing is occasionally it will finish a 100 mile+ run showing 33 or 34mpg. It's the inconsistency that is so puzzling.

My garage has a generic diagnostics rig by (I think) Snap-On so I'll take your advice and seek out an indy with Star. Will any Merc indy with Star Diagnostics be able to glean more info or does it need to be a Merc commercial indy in particular?

 

[Kev555]

Hi Mikeybee, I never really considered onboard fuel average computers as very accurate MPG indicators on any vehicle. With a V6 if you get over 30 on short runs your laughing. the only explanation I could give you is you could have issues with the injectors that is giving erratic readings on the dash display, Seek out an indie with star if theres one in your area, they would have star and better than that years of knowledge to get to the problem quickly. Dont go near Mercedes commercial for diagnostic work unless you've got very deep pockets or someone can recommend a really good one but the hourly rate they charge is a killer . Some of the other Forum users might be able to point you to a good Merc indie in your area?

 

[Kev555]

Theres a guy on the forum here Mikeybee, his username is Star and he's in Reading. He is a forum supporter and a Merc Indie. Hes helped me out a lot in the past on the forum here with advice.

 

[Craiglxviii]

The OM642 is a pretty hungry engine. We have had two, an E320 estate and now an R320 LWB. Both cars have averaged 27-28mpg combined; the R320 had an injector seal go which was losing fuel efficiency; we had that repaired and that car will now see 32-33mpg on a run.

MB mpg read outs calculate in a funny way. They start off the journey at “nominal” say 25mpg, but as soon as you pull away they drop to a rolling average of the last 10 seconds. So that 25 may fall to 8. Then, every 10 seconds or so the mpg readout will update and change by no more than 0.1mpg each time. So, it might take 150 miles for that readout to show an accurate reflection of the actual fuel burn realised. I’ve noticed that it’s quite usual for my “miles remaining” readout to increase constantly for the first half of a long trip.

 

[MikeyBee]

The OM642 is a pretty hungry engine. We have had two, an E320 estate and now an R320 LWB. Both cars have averaged 27-28mpg combined; the R320 had an injector seal go which was losing fuel efficiency; we had that repaired and that car will now see 32-33mpg on a run.

MB mpg read outs calculate in a funny way. They start off the journey at “nominal” say 25mpg, but as soon as you pull away they drop to a rolling average of the last 10 seconds. So that 25 may fall to 8. Then, every 10 seconds or so the mpg readout will update and change by no more than 0.1mpg each time. So, it might take 150 miles for that readout to show an accurate reflection of the actual fuel burn realised. I’ve noticed that it’s quite usual for my “miles remaining” readout to increase constantly for the first half of a long trip.

How very interesting! I was musing about how the mileage computer calculates fuel consumption on my trip home tonight from my boat (1935, 7 litre, 44hp vintage diesel, ticks over at 160rpm ). 79 miles of mostly good A roads and motorway, 28.8mpg on arriving home according to the dash display today. Did it work that out at 28.8mpg for the whole trip or was it 28.8mpg over the last five miles?

I've started noting the mileage at each brim-full fuel refill so I can do some basic arithmetic and see what the fuel consumption really is.

Other days I might do the same trip and end up the the MPG saying 24, or 34.

 

[MikeyBee]

Theres a guy on the forum here Mikeybee, his username is Star and he's in Reading. He is a forum supporter and a Merc Indie. Hes helped me out a lot in the past on the forum here with advice.

That's most helpful, I'll seek him out. I spend half my working life in Reading!

 

[Craiglxviii]

How very interesting! I was musing about how the mileage computer calculates fuel consumption on my trip home tonight from my boat (1935, 7 litre, 44hp vintage diesel, ticks over at 160rpm ). 79 miles of mostly good A roads and motorway, 28.8mpg on arriving home according to the dash display today. Did it work that out at 28.8mpg for the whole trip or was it 28.8mpg over the last five miles?

I've started noting the mileage at each brim-full fuel refill so I can do some basic arithmetic and see what the fuel consumption really is.

Other days I might do the same trip and end up the the MPG saying 24, or 34.

Go and download the Road Trip app. Can’t recommend it highly enough. It’ll do all your trip to trip calcs. Example (this is the E320):



re. your question on the 28.8mpg. If the readout had been steadily climbing up to that value by the time you reached destination, then it’s likely it would have exceeded it over the whole trip. The way the value displayed is calculated means that it is “weighted” towards the longest period of average mpg at or around that value. Example, I recently drove my new (to me) S Class back home. I got 33.2mpg all the way down the M1, but that dropped to 31.2 by the time we arrived back home; the last 20 miles dropped 10% of the rolling average of the preceding 120 miles.

 

[Kev555]

That's most helpful, I'll seek him out. I spend half my working life in Reading!

Search him out on the forum here Mikeybee in the members section and drop him a PM

 

[Craiglxviii]

@star one for you Ian!

 

[MikeyBee]

@star one for you Ian!

I've found Star on the forum thanks and had a look at his business website. Prior to pestering him with possibly nothing, I've downloaded the Road Trip app you recommended and I'll use it to check my real life actual fuel consumption. If I'm actually getting the 29.1 claimed by long term trip display then this appears to be reasonably typical for this lovely engine it is just the short trip display being misleading! Nothing like getting oneself properly informed and up to speed prior to engaging a professional. I generally find professionals like dealing with well-informed punters too

 

[star]

Thanks for the recommendations, however we don’t work on vitos. Have you had any software updates, I’ve heard that this can affect consumption.

 

[tjamesbo]

My Vito (2007 120CDI ) i get 31-32 on runs staying at the legal limits 31-32 on the motorway journeys I'm at 215K mls now
do get a few where it drops wind / temperature ? I wondered about swapping to a 2.1 4 cyl but in reality i dont thinks the savings are worth the trouble and that V6 is so smooth and refined once had its hard to go back

 

[MikeyBee]

Thanks for your comments tjamesbo. I have to admit I tend to drift up towards 80 on the speedo on the motorway which is probably 75-76-ish if measured accurately. I've done the run up to the boat repeatedly over the last two or three weeks and most times the trip display finished the journey saying 28.<something> mpg. EXCEPT for one trip when it claimed 32mpg. I just have the feeling that the 32 mpg is what it ought to be returning on every trip, and something is intermittently wrong to cause the 28mpg trips.

I agree with you though, it is such a delightful engine to drive that I'll just swallow the appalling fuel economy while I am earning the money!

I do find it irksome though, when it goes in for service or repair and the garage lends me a fun-to-drive little Fabia VRS which is nimble, quick and still does approaching 60 mpg driven hard.... grrr...

 

[M80]

The best I ever saw from my V6 Viano was a fraction over 32mpg, and I drove it for economy. I'm happy to set cruise at 58 and let everyone fight for space in the outer lanes.
I was never even close to happy with the economy and it could easily fall to 26 mpg.

You may find that the regeneration is upsetting your economy on some journeys?? I haven't had many vehicles with the DPF but felt it was inefficient on the 642, mine at least.
The 646 Vito's I've had could see 42mpg, no DPF.
The 651 Viano (with DPF) never had the chance to run an 'efficient ' journey, but did show over 38mpg once. In truth the power, smoothness and quietness of the 651 compares to the 642 imo, but I'm not racing it. On the hills round here it would perform well enough.
The lower ratio diff is nicer on the 642.

For me the better set up is the 646 engine, no DPF. It is far simpler and more robust, although more gruff.
But I would remap, replace tyres for 205/75/16 for a greater pneumatic suspension and replace the diff for a 642 diff.
The DRL's and mirrors are nicer on the later 639 though.

 

[MikeyBee]

Just to wake up this old thread I've slowly come to terms with 28mpg.

In summer the fuel consumption can easily rise to 35mpg on a long trip but never in winter or cold weather. Having spent a year or two carefully paying attention, the fuel consumption seems best on the motorway if I engage the cruise at a shade under 70mph but the air temp outside seems to have a big effect. The colder it is, the poorer the fuel consumption. It can be down below 25mpg for 50 miles on a cold winter's morning yet in summer at 22c it gets up to 30+mpg within 20 miles.

Having driven a few other possible vans recently I realise I'm hooked on the luxury of this divine V6 motor. I'm just gonna keep on shovelling in the diesel and enjoy what's left of my life

Thanks for all the replies everyone. I have another curious problem I'll start a new thread on...

 

[Blobcat]

Just to wake up this old thread I've slowly come to terms with 28mpg.

In summer the fuel consumption can easily rise to 35mpg on a long trip but never in winter or cold weather. Having spent a year or two carefully paying attention, the fuel consumption seems best on the motorway if I engage the cruise at a shade under 70mph but the air temp outside seems to have a big effect. The colder it is, the poorer the fuel consumption. It can be down below 25mpg for 50 miles on a cold winter's morning yet in summer at 22c it gets up to 30+mpg within 20 miles.

Having driven a few other possible vans recently I realise I'm hooked on the luxury of this divine V6 motor. I'm just gonna keep on shovelling in the diesel and enjoy what's left of my life

Thanks for all the replies everyone. I have another curious problem I'll start a new thread on...

You could try 2EHN or Dipthane - a few posts on here - I keep meaning to get some to try in my smart

 

[MikeyBee]

You could try 2EHN or Dipthane - a few posts on here - I keep meaning to get some to try in my smart

Thanks! I'll have a proper search and a goggle tomorrow, so tired now....

 

[M80]

I use it sporadically.
It feels perhaps a bit smoother, but I can't say I've noticed a consumption improvement. But tbh my comparison's aren't scientific.