E400 cab shocking(?) MPG

[SpikyMikey]

I would start with the basics, a bottle of Redex/Forte/Millers fuel injector cleaner, or just a thankful of premium petrol e.g. Shell V-Power, possibly coupled with 'Italian tune-up', then see how it goes. Terraclean could ne next.

I'd be tempted to also pull the air filters just to check they are OK.

 

[C270 CDI]

Further update - I had the car serviced last week and while it was in got the injectors tested. I don't know what the numbers mean but 1 2 3 5 and 6 were pretty constant but no.4 was a lot higher reading, so that one's getting replaced next week. I had then replace the plugs aswell and my range on dropping the car off was 165-odd (having driven it there nice and slow), and when I drove it home it went up to 300 - so some improvement seen already.
Fingers crossed the injector replacement will make it all OK again, and the best bit is the warranty are covering the cost of the injector and diagnosis so all in all not too painful!

 

[W1ghty]

Further update - I had the car serviced last week and while it was in got the injectors tested. I don't know what the numbers mean but 1 2 3 5 and 6 were pretty constant but no.4 was a lot higher reading, so that one's getting replaced next week. I had then replace the plugs aswell and my range on dropping the car off was 165-odd (having driven it there nice and slow), and when I drove it home it went up to 300 - so some improvement seen already.
Fingers crossed the injector replacement will make it all OK again, and the best bit is the warranty are covering the cost of the injector and diagnosis so all in all not too painful!

That sounds like a positive step forward buddy .

 

[C270 CDI]

Yeah I'm hoping so, I'll keep the updates coming when it's been fixed.

 

[geoffus]

Is it due a service, plugs, air filter etc ?

I did ask this earlier

 

[clk208]

Premium 97+ fuel in my CLS with the 3.5 petrol engine always gives about 20% more MPG across the board. Absolutely gobsmacking difference that isn’t replicated across other cars I drive.

 

[ALFAitalia]

Personally I think that's unlikely....especially on a car that's designed to run on 95 ron and so can't advance the ignition enough to take advantage of the extra knock resistance. In any car or bike that requires 95 I've never noticed any difference if I had to use higher octane stuff for any reason. 20 percent is a lot.

 

[clk208]

Personally I think that's unlikely....especially on a car that's designed to run on 95 ron and so can't advance the ignition enough to take advantage of the extra knock resistance. In any car or bike that requires 95 I've never noticed any difference if I had to use higher octane stuff for any reason. 20 percent is a lot.

I’ve owned the car since it was 4 years old- it’s now 17. The first 8 years I pretty much always used 95 but then switched to 97 I think when they started including 10% ethanol and didn’t switch back to the increased mpg of the good stuff. Tyres are the same model of Goodyear. Only other real variable being I ditched main dealer servicing and moved to a specialist who uses MB approved 5w30 instead of the 0w30? MB used and actually changed the air filter. I guess I’m older and now have 2 kids so might be driving a bit more sedately, but most of my miles are solo.

Mine is the CGI variant. There’s something in the handbook saying low sulphur petrol will give you much better MPGs so that may be a factor

 

[Doodle]

Mine is the CGI variant. There’s something in the handbook saying low sulphur petrol will give you much better MPGs so that may be a factor

As far as I'm aware, all petrol sold on UK forecourts is ULSP (ultra low sulphur) regardless of octane.

 

[Mark9999]

it can be worth running older engines on higher octane fuels, as engines build up carbon deposits they become more prone to pre ignition, If detected the knock sensor would retard the ignition to compensate.
Mark

 

[C270 CDI]

Injector replaced, made zero difference to fuel economy - I averaged 34.6 on a 130 mile drive today. But that drive was to chop it in for a CLS 350CDI so hopefully my mpg worries are in the rear view mirror!!!
Loved the e class but the one I had cost a fortune to put the various issues right so for now I'm being sensible.

 

[Mark9999]

Injector replaced, made zero difference to fuel economy - I averaged 34.6 on a 130 mile drive today. But that drive was to chop it in for a CLS 350CDI so hopefully my mpg worries are in the rear view mirror!!!
Loved the e class but the one I had cost a fortune to put the various issues right so for now I'm being sensible.

Enjoy your new ride.
Mark

 

[C270 CDI]

Thanks. It's no e class but I'm impressed with the comfort and to be fair it's quick. I'll probably keep it a year then maybe see what's around.

 

[fabes]

The CLS should 'ride' as good if not better than an E class, wheels, tyres and tyres pressures dependent......

You could get close(r) to 50 mpg as well

Enjoy!

 

[C270 CDI]

Well I drove it pretty sensibly, only floored it a couple of times. 130 miles of dual carriageway and some a-roads and I got 46.somerhing so I'm happy with that.
I found an adblue tank in the boot but can't work out how to see how much is left in there. It's a 65 plate and on my 65 plate c250 I had I could see the level in the dash menus but can't find anything anywhere on this one. Apparently it'll tell me when it's getting low so I'll just wait for that to happen I guess!

 

[Smart320]

Adblue , work of the devil

 

[Smart320]

But congratulations on the new wheels and at last a decent mpg

 

[W1ghty]

Well I drove it pretty sensibly, only floored it a couple of times. 130 miles of dual carriageway and some a-roads and I got 46.somerhing so I'm happy with that.
I found an adblue tank in the boot but can't work out how to see how much is left in there. It's a 65 plate and on my 65 plate c250 I had I could see the level in the dash menus but can't find anything anywhere on this one. Apparently it'll tell me when it's getting low so I'll just wait for that to happen I guess!

Got some of the adblue anti crystal additive for it .

 

[T5R+]

I found an adblue tank in the boot but can't work out how to see how much is left in there. It's a 65 plate and on my 65 plate c250 I had I could see the level in the dash menus but can't find anything anywhere on this one. Apparently it'll tell me when it's getting low so I'll just wait for that to happen I guess!

Do not wait for the message on the dash. Keep it topped up with fresh AdBlue periodically.
You may actually have a vehicle with no way to check how much liquid in the tank other than "dip it" - may sound comical on a 2015 MB - but you may need a "lollipop stick".


CLS is a cracking choice.

 

[C270 CDI]

Yeah I was thinking I might have to dip it, and I agree on a 2015 car it's a bit agricultural!!