poor fuel economy on E320 CDI

[ckember]

I have been getting poor fuel economy on my 57 plate E320CDI. I thought the cobmined cycle should give me around 37mpg, but I seem to be getting 28-32mpg best. it has 5K miles on the clock.

For the same journey in my old 53 plate C270 CDI I would get around 37-42mpg.

I was hoping that the newer 3.0 V6 would be more efficient than my old 5 cylinder unit.

Do I have an issue, should I wait until the first service and let the engine run in a bit more?

 

[A210AMG]

Hello

My Dad has a 2003 E320cdi Estate bought from new and now with 70K miles. His is 37mpg average, regularly over 40mpg and on a trip from Chester to Dover saw 50mpg once.

What sort of journeys are you doing and are you heavy footed? I think your engine is slightly different to my dads but would expect more?

I would want to see 28mpg out of an ML320CDi so the E must do more than that?

My bus does 25-28 on a run with 3.7 litres and slab like.

 

[BTB 500]

5K miles is probably not fully run in. Also remember that the particulate filtering etc. on modern engines does affect the economy.

What's the book fuel consumption (combined)?

 

[BTB 500]

I would want to see 28mpg out of an ML320CDi so the E must do more than that?

I'm just cracking the 30 mpg barrier with my V6 CDI Vito now on a 50 mile trip at moderate speeds (75 max). It's done about 2,800 miles, and I'm expecting it to loosen up for a while yet.

 

[ckember]

5K miles is probably not fully run in. Also remember that the particulate filtering etc. on modern engines does affect the economy.

What's the book fuel consumption (combined)?

book values are 28 urban, 47 extra urban and 37 combined. I am not driving particular fast 80 tops, which was the same as in the C270. thduring the inital 2.2K before I purchased the car it averaged 26.5, this has changed little. over the next 3k miles I have down in the last 6weeks

I will do a brim to mrim comparison on the next tank to see what that gives.

 

[Dieselman]

Give it a good caning up a steep hill and see if it improves but be warned Euro4 cars are less efficient than Euro3 cars.

 

[A210AMG]

28 cannot be right surely?

might as well have an E500 ? Don't think my dads ever seen less than 30, and probably no less than 35

I agree it 'should' get better but it does sound low?

 

[maddog]

Well with my w210 i have never seen 50mpg not even driving at 50mph with the air con and everything else off

With the cold weather i'm seing 4-6 mpg less than in summer and mine was noticably better on fuel after it had done 20,000miles

 

[A210AMG]

Maddoog,

My dad only saw 50mpg once on a trip from Chester to Dover, just keeping up with traffic..

He is always impressed how well his does.

He had a C220cdi coupe when his was in for a service and was disapointed that only did 35mpg

maybe its how you drive and his has losened up now (70K)

 

[TomTanderson]

I have a 57 E280CDi (which is based on a similar engine) with 2500 miles on the clock and am getting similar mileage and am similarly disappointed.

Admittedly I do quite a lot of urban driving and on the open road I can push the speed a bit but even the "bosses" best is about 33-34 and that is at a pretty steady 60-70.

So far this is no improvement on my petrol V70 and I'm paying 10% extra for the fuel

 

[maddog]

Maddoog,

My dad only saw 50mpg once on a trip from Chester to Dover, just keeping up with traffic..

He is always impressed how well his does.

He had a C220cdi coupe when his was in for a service and was disapointed that only did 35mpg

maybe its how you drive and his has losened up now (70K)

I've had mine from 2001 and its just gone over 60k in those 7 years i've had a best of 48mpg , just the once when i was about to run out of fuel and was trying to get the best mpg i could , tucked behind a truck with the air con radio heaters etc all off and the cruise set to 50mph .

Best i could replicate since was 43mpg.

Year on year i have got 34.5mpg average from my car over summer and winter

 

[A210AMG]

Is a 2001 the older shape? maybe the newer one is a little bit more sleak.... hence the extra couple of Mpg..

 

[Soltan]

Hello

My Dad has a 2003 E320cdi Estate bought from new and now with 70K miles. His is 37mpg average, regularly over 40mpg and on a trip from Chester to Dover saw 50mpg once.

What sort of journeys are you doing and are you heavy footed? I think your engine is slightly different to my dads but would expect more?

I would want to see 28mpg out of an ML320CDi so the E must do more than that?

My bus does 25-28 on a run with 3.7 litres and slab like.

OK, something definitely wrong with my car then, I've got a 2003 E320 CDI Estate as well, and the BEST I've ever got out of it is 40MPG. Admittedly I've probably got a heavy right foot, but even when slowed by traffic (most of my journeys are long Motorway commutes) I average 38MPG for a trip lasting from 1.5 hours to 2 hours.

 

[Ratz]

One word of caution I would add here is that I see a significant fall off in my fuel economy when the weather gets cold. I see anything from 28mpg of largely urban driving to 50mpg on a 50+ mile run.

 

[Rory]

OK, something definitely wrong with my car then, I've got a 2003 E320 CDI Estate as well, and the BEST I've ever got out of it is 40MPG. Admittedly I've probably got a heavy right foot, but even when slowed by traffic (most of my journeys are long Motorway commutes) I average 38MPG for a trip lasting from 1.5 hours to 2 hours.

I have a C270CDi auto estate.

One thing I would say is that how you drive makes a *huge* difference with these car. They're pretty heavy cars and building up speed after slowing down uses a lot of fuel. Stopping completely is an absolute disaster.

Have you tried getting on a quiet motorway, setting the cruise control for 70 and then reseting the trip? It will reset to some number (I'm not sure if it's a default number or the cars own average) but then it should quickly start increasing towards 50MPG.

Most I've had on a 200 mile, 70MPH steady motorway run is 52MPG. But if press on even a bit, driving at say 85, pushing and braking in the concertina action in lane 3, then it'll be more like 40MPG. Around town - 5mile runs from cold - it's doing low 30's.

 

[Satch]

OK, something definitely wrong with my car then, I've got a 2003 E320 CDI Estate as well, and the BEST I've ever got out of it is 40MPG. Admittedly I've probably got a heavy right foot, but even when slowed by traffic (most of my journeys are long Motorway commutes) I average 38MPG for a trip lasting from 1.5 hours to 2 hours.

That sounds about right. I frequently see around 37/38-ish reported as the long distance touring mpg..

 

[Soltan]

Hmmm, OK, I'll try your suggestion Rory, I've done it before and got about 40MPG on a run up the M40. Trouble is I never seem to hit clear motorways very often and when I do...well let just say that the MPG on the 320CDI falls off rapidly the faster you go!
It just feels weird going so slow with the speedo needle barely half way round the dial

 

[Brian WH]

That sounds about right. I frequently see around 37/38-ish reported as the long distance touring mpg..

Me too and I have just done 5000 miles.

If you go over 70mph the mpg drops rapidly.

Same journey in mine. 30 miles and cruise set as follows, maintaining it where I could.

@ 60mph = 42mpg, 70mph = 40mpg 80mph = 37mph 90mph = 34mpg

 

[Soltan]

Me too and I have just done 5000 miles.

If you go over 70mph the mpg drops rapidly.

Same journey in mine. 30 miles and cruise set as follows, maintaining it where I could.

@ 60mph = 42mpg, 70mph = 40mpg 80mph = 37mph 90mph = 34mpg

Wow, pretty conclusive I'd say. Nice work Brian WH.
Still, if it puts a smile on your face you have to ignore the MPG sometimes

 

[BTB 500]

let just say that the MPG on the 320CDI falls off rapidly the faster you go!

Not half as much as it does with my Vito!

(which is actually reasonably sleek for a van)