E350d Terrible mpg SOLVED

[E55BOF]

Old adage: "There's no such thing as a cheap Mercedes". Expensive cars when new still have the same running costs when they get old and can be bought cheaply. This includes fuel consumption...

 

[Daddyoftwo]

Just to say economy is still a lot better than it was. Can get 45mpg on trip from Manchester to London when smart motorway upgrade and speed camera signs means a light right hand foot.

And 28mpg ish on short journeys around town.

Rarely see the 14.1mpg indicator that I used to always see for the first mile or two of any journey.

Obviously nowhere near Merc claims for mpg - but much more acceptable, especially with diesel at £1.76 a litre.

Don't know if it was the Terraclean and / or the thermostat. Suspect mainly the thermostat.

 

[Daddyoftwo]

Old adage: "There's no such thing as a cheap Mercedes". Expensive cars when new still have the same running costs when they get old and can be bought cheaply. This includes fuel consumption...

So far, I've not found it a particularly expensive car to run (touch wood). Insurance would be expensive at a group 43, but I'm in my mid fifties with full NCB - so my last renewal was I think £550. Don't do a big mileage - so I probably pay about a grand more on fuel than say a Nissan Micra which might do 55mpg.

Servicing and parts are quite expensive but so far it's been fairly reliable and I repair most small bits and bobs myself. Hopefully minimal depreciation.

Certainly much cheaper to run than my first car, a Morris Ital that nearly bankrupted me in three months of ownership as a student, and a Saab 9-3 2.2d which I couldn't drive off the dealers forecourt without another £500 bill.

I guess that running costs are about £2000pa more than running the cheapest car possible.

 

[Deano24v]

can only dream of 50mpg, i get happy when my trip comp clicks over (just) into forty on my 200 mile commute to work

I think mine has had the emissions update though so will get that reversed but i never expected to get anywhere near the 47 long term average. That said, i do only do motorway journeys. Coolant temp sticks bang on 90c on the gauge. But the car is 2 tonnes, has stupidly wire tyres that dont help economy and my driving doesnt lend itself to it either, so all things being said 40 is ok with me

 

[W1ghty]

Just to say economy is still a lot better than it was. Can get 45mpg on trip from Manchester to London when smart motorway upgrade and speed camera signs means a light right hand foot.

And 28mpg ish on short journeys around town.

Rarely see the 14.1mpg indicator that I used to always see for the first mile or two of any journey.

Obviously nowhere near Merc claims for mpg - but much more acceptable, especially with diesel at £1.76 a litre.

Don't know if it was the Terraclean and / or the thermostat. Suspect mainly the thermostat.

I ended up changing my thermostat the other week , turns out it was reacting at all when I put the old one in boiling water so , it’s a good thing I did . The car was returning 47mpg on a long run back from Wales with the new stat in .

What Have You Done To Your Merc Today? | General Discussion

Changed this on the C200 Kompressor today: The old one has been split for some time thanks to my heavy-handedness ....... :( MERCEDES C-CLASS CL203 COUPE SPARE WHEEL HOLDER CLAMP £9.95 delivered. MERCEDES C-CLASS CL203 COUPE SPARE WHEEL HOLDER CLAMP 5011727134010 | eBay

forums.mbclub.co.uk

 

[Daddyoftwo]

can only dream of 50mpg, i get happy when my trip comp clicks over (just) into forty on my 200 mile commute to work

I think mine has had the emissions update though so will get that reversed but i never expected to get anywhere near the 47 long term average. That said, i do only do motorway journeys. Coolant temp sticks bang on 90c on the gauge. But the car is 2 tonnes, has stupidly wire tyres that dont help economy and my driving doesnt lend itself to it either, so all things being said 40 is ok with me

Hi Deano

Mine was originally going up to I think 80-90 degrees when it was broken - I think that it is supposed to go up to about 95-100 degrees - quite a bit past the half way point on the gauge. If it is not getting up to temperature properly then it could well be giving crappy economy (and I am guessing filling your engine up with soot).

The thermostat on mine was silly expensive, I replaced it beginning of COVID lockdown when it was really hard to get parts. It was about £150 plus fitting (another £80 odd) and was glad to get hold of one let alone get a bargain. think that there is a cheaper thermostat without an electronic sensor on some models. (On my old Jag X Type it was about £12 and I was able to fit it myself). In anycase you don't want to replace it unless it has gone wrong.

But the way to tell if it is stuck open (or more likely the internal rubber seal has perished - so only half working as water can get around the seal) is that a few minutes after you have started it up, hot water should not be going into the radiator (or returning) and so the radiator hoses should not be heated up until it is has reached maximum operating temperature and the thermostat has opened.

Good luck.

 

[DSM10000]

I think mine has had the emissions update though so will get that reversed

If Mercedes have applied the emissions software update then I believe you cannot reverse it

 

[E55BOF]

can only dream of 50mpg, i get happy when my trip comp clicks over (just) into forty on my 200 mile commute to work

I think mine has had the emissions update though so will get that reversed but i never expected to get anywhere near the 47 long term average. That said, i do only do motorway journeys. Coolant temp sticks bang on 90c on the gauge. But the car is 2 tonnes, has stupidly wire tyres that dont help economy and my driving doesnt lend itself to it either, so all things being said 40 is ok with me

If yours is the facelift with Adblue, then it may have had the update; if pre-facelift, then I don't think there was one for it. My 2013 CLS SB 350 CDI gets up to averaging about 36 mpg eventually on a motorway run, but that is cruising at about 85 (on the continent, obviously... ).

 

[OneForTheRoad]

can only dream of 50mpg, i get happy when my trip comp clicks over (just) into forty on my 200 mile commute to work

I think mine has had the emissions update though so will get that reversed but i never expected to get anywhere near the 47 long term average. That said, i do only do motorway journeys. Coolant temp sticks bang on 90c on the gauge. But the car is 2 tonnes, has stupidly wire tyres that dont help economy and my driving doesnt lend itself to it either, so all things being said 40 is ok with me

A remap will gain 10 % , abuse the extra oomph and you'll lose 20 % . What speeds do you find gets you better mpg . I think 75 mph is a sweet spot tbh.best I've seen is a trip to hull ,46mpg 9th gear ,over 250 miles .

 

[suty455]

Remapped and no emissions controls fitted with a custom exhaust and larger intercooler I average 44 overall with mixed use, bit less if I do a lot round Town it can drop to 38 with gentle driving, if am a good boy on the motorway and stick at 65-70 I can nudge 50mpg my norm is 75-80 between roadworks, however the extra oomph is am afraid addictive so there are Days when my mpg is woeful but the smile is large

 

[Daddyoftwo]

Hi Deano

Here's where my thermostat gets to. It gets there pretty quickly even in winter - say within 2 miles. I think that it's technically 95 degrees.

With the old thermostat, with the perished seal, it only got to just over half way, took about 5 miles to get there. I lost about 10mpg and there's no error codes. And the car feels like it's running better



But as I said it's easy to verify if it's not working correctly.

All the other guys claiming mid 30s mpg on a run might also have perished thermostat seals as apparently the Mercedes rubber only has a limited life!!

 

[E55BOF]

A remap will gain 10 % , abuse the extra oomph and you'll lose 20 % . What speeds do you find gets you better mpg . I think 75 mph is a sweet spot tbh.best I've seen is a trip to hull ,46mpg 9th gear ,over 250 miles .

If it's a pre-facelift, it only has seven gears. Then again, though, it doesn't have Adblue, which is a trade-off I'm very happy with; from what I've seen, the MB Adblue system is often troublesome, and expensive to fix when it is...
I can't say what economy I would get cruising at 70 mph. I might find out one day when the traffic is very heavy...

DaddyofTwo, that's 90 degrees; exactly where it should be.

 

[Daddyoftwo]

If it's a pre-facelift, it only has seven gears. Then again, though, it doesn't have Adblue, which is a trade-off I'm very happy with; from what I've seen, the MB Adblue system is often troublesome, and expensive to fix when it is...
I can't say what economy I would get cruising at 70 mph. I might find out one day when the traffic is very heavy...

DaddyofTwo, that's 90 degrees; exactly where it should be.

Public forum - so even if I accidentally hit 71mph that was only by accident.

It is a 7G pre facelift.

It is I think a tad over 90 degrees - engine may have cooled whilst I was fishing out my phone to take the photo.

 

[OneForTheRoad]

Public forum - so even if I accidentally hit 71mph that was only by accident.

It is a 7G pre facelift.

It is I think a tad over 90 degrees - engine may have cooled whilst I was fishing out my phone to take the photo.

How many pass you on a motorway , please !!!!!

 

[Deano24v]

Hi Deano

Here's where my thermostat gets to. It gets there pretty quickly even in winter - say within 2 miles. I think that it's technically 95 degrees.

With the old thermostat, with the perished seal, it only got to just over half way, took about 5 miles to get there. I lost about 10mpg and there's no error codes. And the car feels like it's running better


View attachment 126617
But as I said it's easy to verify if it's not working correctly.

All the other guys claiming mid 30s mpg on a run might also have perished thermostat seals as apparently the Mercedes rubber only has a limited life!!

Thats bang on where mine sits. Gets up to temp nice and quickly as well like you say.
I don't think there is anything wrong with mine. I got 43.5 on the drive back from London last night so I think that's pretty good. No where near what my old 535d would do but it sounds like it's about right for the car so I'm not unhappy.

 

[giusepppe]

Hi Daddyoftwo, where do you go to get it terra cleaned. ???