Disillusioned with Diesel

[MBDevotee]

Hi All,

Recently bought a CLK 270CDi with just under 60k on it (so well run-in).

My old petrol CLK 320 used to do about 27-28mpg on the trip computer and about 26-27 mpg based on litres used and miles covered.

This was converted to LPG, and then returned the same on the trip computer but an actual of 25mpg - giving the equivalent of around 50mpg.


So my logic of buying the 270CDi was that I should get upper 40's perhaps up to 50mpg overall.

Initially it looked promising - my collection trip yeilded 61 mpg all the way home until I got off the motorway, this then dropped to 49 by the time I got home (driving reasonably gently) on the trip computer.

However - now I have had the car a few weeks, and settled into my normal routine, I am only getting 44.1 on the trip computer - but very concerningly, 37.4 if I actually measure it with fuel in the tank and miles covered.

This seems to be pretty dire for a small car with a diesel engine. I would have expected late 40's at the very worst and into the 50's on longer runs.

I intend to get the car chipped for better economy, but wondered what typical fuel consumption is for most people with the 2.7 CDi engine.

Certainly beginning to wish I'd gone CLK 350 (which I could have easily got for less money than the 270) and LPG'd it - it would have been smoother, quieter, faster, and on the initial appearance, more economical as well....

 

[Juddian]

Ah the true reality of using a Diesel for other than constant speed motorway mile munching or touring type of steady motoring.

Once you get into normal cut and thrust of the daily grind and start using the boost more, the fuel slurps in...i found this to be the case in one of my first turboDiesels, the much lauded Pug 306td, yes it went like a scalded cat but boy could it drink some juice unless you drove like a saint, 35 mpg was about normal where 55 was a long journey figure, hardly worth the extra costs.

Even my 2.0 litre first model td Avensis could get through some juice under load, on holiday just mincing about i though the gauge had packed up such was the difference.

Previous NA Diesels were economical no matter how you drove them, they didn't have this sting in the tail of actually using the power...mind you they didn't have much power to use..

I'm sticking with LPG for the forseeable, probably till the bunch of crooks masquerading as the govt decide to raise tax levels on the stuff to petrol equivalent, then i'll probably hang me driving gloves up and stop paying off the national debt THEY got us into.

Its not just fuel costs though, the horrendous bills that modern Diesels with all the electronic and emissions junk now fitted i simply don't need to risk any more, they are no longer the simple, robust durable and easily fixed all mechanical jobbies i ran for donkeys years without the slightest bother.

The thing i miss least about Diesel is listening to that tractor engine at tickover.

 

[Remenham]

Sorry but from my experience with 320cdi diesels your economy expectations were highly unrealistic. Even if you can get a good figure cruising at 50 to 70 your overall figures will be destroyed down by any town driving.

Personally I would call a CLK a medium rather than small car which would be a Fiesta or suchlike.

 

[Shezbo]

Hi All,

Recently bought a CLK 270CDi with just under 60k on it (so well run-in).

My old petrol CLK 320 used to do about 27-28mpg on the trip computer and about 26-27 mpg based on litres used and miles covered.

This was converted to LPG, and then returned the same on the trip computer but an actual of 25mpg - giving the equivalent of around 50mpg.


So my logic of buying the 270CDi was that I should get upper 40's perhaps up to 50mpg overall.

Initially it looked promising - my collection trip yeilded 61 mpg all the way home until I got off the motorway, this then dropped to 49 by the time I got home (driving reasonably gently) on the trip computer.

However - now I have had the car a few weeks, and settled into my normal routine, I am only getting 44.1 on the trip computer - but very concerningly, 37.4 if I actually measure it with fuel in the tank and miles covered.

This seems to be pretty dire for a small car with a diesel engine. I would have expected late 40's at the very worst and into the 50's on longer runs.

I intend to get the car chipped for better economy, but wondered what typical fuel consumption is for most people with the 2.7 CDi engine.

Certainly beginning to wish I'd gone CLK 350 (which I could have easily got for less money than the 270) and LPG'd it - it would have been smoother, quieter, faster, and on the initial appearance, more economical as well....

Plus you have the fact diesel is more expensive than petrol element to factor in, therefore petrol cars - £ for £ - would be a closer in real world if the prices were the same. Sorry cannot say which is the better car though

 

[Rory]

However - now I have had the car a few weeks, and settled into my normal routine, I am only getting 44.1 on the trip computer - but very concerningly, 37.4 if I actually measure it with fuel in the tank and miles covered.

What's your "normal routine"?

Mine is just about to tip over 60K miles. I reckon the MPG readout is a little optimistic but it's hard to compare for sure as it's difficult to fill the tank up consistantly.

I live in a semi-rural area but work from home and generally only use the car for long business trips. On a 400 mile steady motorway run at 70ish it'll just about break 50MPG. Starting from home, I have a 23 mile A road journey to get to the motorway. The car will drop to about 30MPG and then gradually climb towards, and might just break, 40MPG by the time I get to the motorway. It then slowly creeps up once I settle on the motorway.

Now and again I used to run my wife into town to work, so that's a 12 mile round trip in fairly busy traffic and I'd see low 30's for the trip.

One thing is these engines take a lot of warming up - mine runs at a rock steady 85C but it takes a decent journey to get there.


If you saw 60+MPG (I've never seen anything like that) then you must know what you're doing, but the trick is to use the torque and almost let the car drive itself, and try to keep the speed up as much as possible. Mine will run for ages on the over-run (foot off the gas pedal) and you can watch the MPG clicking up, but then getting back up to speed again seems to more than lose those gains. I avoid actually stopping if at all possible - stop start driving kills the MPG in a diesel auto.

 

[Xtractorfan]

Anyone getting the equivalent of 50mpg from a car , then deciding to change to an alternatively fuelled vehicle would be well advised to do a lot of homework before committing....
The only good thing is your 270 CDI will still be a very saleable vehicle if you should so decide..

 

[Alex M Grieve]

I live in a semi-rural area but work from home and generally only use the car for long business trips. On a 400 mile steady motorway run at 70ish it'll just about break 50MPG. Starting from home, I have a 23 mile A road journey to get to the motorway. The car will drop to about 30MPG and then gradually climb towards, and might just break, 40MPG by the time I get to the motorway. It then slowly creeps up once I settle on the motorway.

Now and again I used to run my wife into town to work, so that's a 12 mile round trip in fairly busy traffic and I'd see low 30's for the trip. .

That exactly matches my experience in each of several cars, for the journey to the motorway, and for motorway travel. Indeed, when I go down the M40 from Junction 15 I am showing a journey average in the low 40s when I get to the M25, then once on the M25 on the way round to the M3 (about 20 miles I think), because of the variable speed limit which is usually 50 or 60, the average moves up very pleasingly, often by 5 mpg.

I have never seen low 30s in any of my diesels, even driving a W 211 320 CDI in London traffic. As you say, I must be doing something right!

 

[MechPhil]

We've all heard the "60mpg" fairytales, and I must say that I was also expecting high 40's from the 270, but mid 40' aren't exactly "dire". 37.4 mpg on the other hand is pretty low.

Is the car due for a service, by any chance? And does the heat gauge get up to the normal range? Are there any modifications like special alloys or spoilers of any sort? If none of these questions raise any flags, it may be worthwhile to run a decent brand of injector cleaner through it, and have someone check the injectors and the intake manifold...

It really sucks to buy a nice car and be disappointed with the fuel economy, but there might be hop in it yet!

Phil

 

[gary272]

I'm sorry but I think your expectation was a little on the high side.

We have the 320cdi and don't do much mileage. Local it does around 28 which for a big car with a big engine it is all I expect. If we go for a non motorway run out then it quickly climbs to 38ish. Motorway on a 450 mile trip it got to 47.7. All these are based on the cars computer readings.

I don't think you would ever have beaten the lpg figures.

 

[stevenN]

My old E220cdi 2002 with 180k on the clock returns an average of 48mpg according to the computer.
On a good motorway run at a steady 70+mph I get 54mpg
Went to Skegness yesterday so nothing much over 60mph 203 mile round trip at 51mpg
I am not going to complain about that
My previous car was a 03 Megane that averaged 53-57mpg
But was pants, uncomfortable, bland.

 

[whitenemesis]

We've all heard the "60mpg" fairytales, and I must say that I was also expecting high 40's from the 270, but mid 40' aren't exactly "dire". 37.4 mpg on the other hand is pretty low.

Is the car due for a service, by any chance? And does the heat gauge get up to the normal range? Are there any modifications like special alloys or spoilers of any sort? If none of these questions raise any flags, it may be worthwhile to run a decent brand of injector cleaner through it, and have someone check the injectors and the intake manifold...

It really sucks to buy a nice car and be disappointed with the fuel economy, but there might be hop in it yet!

Phil

Not all fairy tales.. (My now sold 270CDI)

OK that trip (repeated many times with similar results) was mainly motorway with A/B start and finish. Mid 50s was easy on a steady run and around town high 30, low 40s routinely acheived

 

[syncropaddy]

Anyone getting the equivalent of 50mpg from a car , then deciding to change to an alternatively fuelled vehicle would be well advised to do a lot of homework before committing....
The only good thing is your 270 CDI will still be a very saleable vehicle if you should so decide..

Well said Sir! A 2.7 litre diesel is not a small one by any stretch of the imagination and to average 40 mpg will be an achievement. I have been driving diesels since 1981 and averaging 50 mpg plus in real conditions isnt that common. I recently had a rented Skoda Octavia for 3 weeks and it had a 1.6 TDi under the bonnet and it averaged 58 mpg which is the best I have ever seen. I am currently averaging 48 mpg in my Passat 2.0TDi

 

[robparker]

When you actually consider all factors of a modern (CDI and newer) Merc diesel.. higher buying price, higher depriciation (than an old car), much higher repair costs, higher price of diesel and real life MPG figures... I cant think that they actually make much sense for that many people, certainly far less than the amount of people the have them.

I'll stick with LPG and my old '84 w123 "tractor" diesel!

 

[T1M4]

This is an interesting thread to read, as I own a 2005 CLK 220 CDI and the economy is much different. I average 53 MPG going to and from work which is 4 miles on country roads 16 on dual carriageway and 2 in town. The best I have got on a motorway run is 56-57. These are correct figures as I always work out the MPG per tank, by using the amount of litres I fill up with and amount of miles travelled.
However, my car is a manual which i know will improve MPG but only slightly and I do drive to try and maximise my MPG.

 

[syncropaddy]

I'll stick with LPG and my old '84 w123 "tractor" diesel!

Im jealous .....

 

[Richard Elliot]

tractor 123 diesels are NOT economical considering their dire performance. 45mpg from a BIG car that will do 130mph and 0-60 in under 10 seconds is excellent, its what I can achieve, but only on a long run. Expecting anything better is totally unrealistic.

 

[robparker]

tractor 123 diesels are NOT economical considering their dire performance. 45mpg from a BIG car that will do 130mph and 0-60 in under 10 seconds is excellent, its what I can achieve, but only on a long run. Expecting anything better is totally unrealistic.

Well my 123 tractor will do 40mpg on a run.. which is ok, but it also cost me £700 to buy, i can sell it for that price any time I want and nothing will go wrong with it in the mean time... so thats far more economical than anything newer. and if you're on the motorway doing 70mph (as appose to 130mph) then its perfectly adequate.

 

[Richard Elliot]

Well my 123 tractor will do 40mpg on a run.. which is ok, but it also cost me £700 to buy, i can sell it for that price any time I want and nothing will go wrong with it in the mean time... so thats far more economical than anything newer. and if you're on the motorway doing 70mph (as appose to 130mph) then its perfectly adequate.

ha ha I've actually got a REAL tractor, 2.7l 3 cylinder NewHolland with 55hp - same as a W123 200D. It won't do 70mph but will pull a flail mower up a 35º incline. The silencer snapped off so it sounds pretty good too.

 

[television]

And I am happy with petrol, the CL has near on AMG performance and it gives me just under 30mpg, I hope to better that on my Swedish trip coming up

 

[EmilysDad]

.....
However - now I have had the car a few weeks, and settled into my normal routine, I am only getting 44.1 on the trip computer - but very concerningly, 37.4 if I actually measure it with fuel in the tank and miles covered........

If it makes you feel any better, my R320 diseasal gets mid/high 20s around town. But it wasn't bought for economy. :lol: