E280 47.9mpg IMPOSSIBLE?

[RKC-benz]

As BlackC55 and i-CONICA said, fuel additives are essentially detergents and clean the fuel system and valves. They do work. If you can't be bothered with additives, then opt for Premium fuels instead - BP Ultimate or Shell V-Power - they contain the required additives in the correct ratios. A few tankful of Premium fuels will do the job. There is also a product called cataclean, though the manufacturers claims are controversial. See http://www.cataclean.com.

Does this apply to petrol too?

 

[Gipsyracer]

I put some injector cleaner in the tank tonight and by the time I get home tomorrow I will have done about 280 miles with it running through the system.

Next step is a brim-to-brim check over a 500 mile run next week. I'll post the results here at the end of the week.

Anyone fancy a sweepstake?

 

[markjay]

Does this apply to petrol too?

Yes it does.

 

[markjay]

Do you think I should try cleaning additives in my 1995 E280 S124? It swallows petrol like it's closing time!

If so, which ones, why, and what will I expect to happen?

The easiest way is to fill up with a couple of tankfuls of Premium fuel.

The cheaper way is adding it yourself, the recommended brands are Redex, Millers, and Forte.

But keep in mind that all it does is clean the fuel system - there may be other reasons why your car is heavy on the fuel.

As for Cataclean... I don't know what to say. Reading about it, it seems that the manufacturer had to withdraw some of the claims they made.

Also, 'Italian Tune-Up' refers to driving the car hard - running the engine at low gear / high rev - after adding detergent, to push as much of the stuff as possible at high pressure through the injectors.

 

[E280wilson]

Wow I wish I could get that mpg from my 280cdi estate. Mine starts at 42mpg when I set off and goes down and settles at around 33. Although I do only work 7 miles away. I'm a steady driver too and change down before the car wants to.
Hopefully my new one will be far better.

 

[dozypillock]

I remember using Formula shell? many years ago, and it burnt out valves on my VW sirocco GTX. It was with withdrawn shortly after, after lots of complaints. Has anybody read/experienced problems with these new premium fuels?

 

[markjay]

I remember using Formula shell? many years ago, and it burnt out valves on my VW sirocco GTX. It was with withdrawn shortly after, after lots of complaints. Has anybody read/experienced problems with these new premium fuels?

Yes I remember that, the issue was that the tanker drivers had the wrong instructions and added too much additives. Shell compensate affected motorists at tbe time.

Shell reintroduced the fuel under the name Shell Optimax, then renamed it to Shell V-Power.

There have been no reported issues in the past 10 years. I use only Shell V-Power for a number of years now without issue.

 

[grumpyoldgit]

I use Millers in every fill, but cannot vouch for the accuracy of the OBD.
This was mainly M5 - M42 - A34 - M3 with cruise set at 70-ish+ mph.

C270-CDI

 

[camerafodder]

What temperature is the car running at?

 

[DrNick]

What temperature is the car running at?

From post 1:
First let's rule out the obvious. 92k miles so just run in, full service history, fastidiously maintained, everything appears to be working right, no black smoke or gearbox over-revving. Running at about 90c, warms up quickly and stays steady. Tyres pumped up to 34psi. Nothing in the boot. No roof rack. I've given it a bit of a thrashing to clear out the cobwebs. Not yet double-checked by brimming the tank.

 

[DSM10000]

It may also be worth having a full 4 wheel alignment carried out. Poor tracking can also add to fuel use.

 

[t-dawg1]

If you have to sport suspension on yours pump your tyres to 36psi all round,I average around 37-39 on mine and on long runs 42mpg is the best iv seen and that with a wife and 2 kids onboard with luggage in boot

 

[Gipsyracer]

Tyres

From OP

Just checked the tyres. 245/45 R17 Michelin X. No obvious scrubbing so alignment can't be a mile out.

Rears due for replacement in a few k miles so will get 4-wheel alignment check done at the same time.

 

[MancMike]

Just checked the tyres. 245/45 R17 Michelin X.

Michelin X?

Michelin X | Longstone Tyres

If you mean Michelin X-ICE, they're Winter tyres, which won't be good for fuel economy at all. They're designed with lots of sipes and very soft compound, so have high rolling resistance.

 

[Gipsyracer]

Tyres

Not winter tyres. Must have missed a few letters off the description. They're just normal ones.

 

[V12]

Tyre 245/45 R17 : discount price, free delivery - Tyre Leader

 

[W210Virgin]

I get an easy indicated mid-40s from my old I6 320CDi and it's at 153k miles. I've had it close to 50 as well. V6 version is even better.
Amazingly efficient engines.

 

[Blowpipe]

I get an easy indicated mid-40s from my old I6 320CDi and it's at 153k miles. I've had it close to 50 as well. V6 version is even better.
Amazingly efficient engines.

Seen an indicated 60.2mpg on my E320; not sure what the real world difference is but I'd say that was pretty good.

 

[camerafodder]

From post 1:
First let's rule out the obvious. 92k miles so just run in, full service history, fastidiously maintained, everything appears to be working right, no black smoke or gearbox over-revving. Running at about 90c, warms up quickly and stays steady. Tyres pumped up to 34psi. Nothing in the boot. No roof rack. I've given it a bit of a thrashing to clear out the cobwebs. Not yet double-checked by brimming the tank.

yeah I knew that

 

[kth286]

Nobody mentioned sticking brake pads.

Crud builds up and they do not slide freely when the brake pedal is released.

It only takes a small amount of constant rubbing against the disc to have an appreciable mpg affect.

Take all the pads out and give them a good clean, and coat the sliding edges with copper grease.

Then report back.