E320 CDI Consumption

[Homer]

Hi All

I have just bought a 2000 E320 CDI Avantguarde Auto (back to Merc's after 7 years of BMW motoring) and I'm a bit surprised with the fuel economy.

Around town, after resetting the odometer twice, it is giving around 230 miles on a full tank, which is around the same as my old 523i Auto. On the computer I am getting around 25-30mpg.

Part of the reason of moving to diesel was to improve the economy, is this normal or could someone give some ideas on areas to investigate. After speaking to my mechanic, he said to reset the computer to the factory default, as the previous owner may of had be tuned to sports performance rather than economy.

Thanks

 

[blassberg]

what do you get on a longer run?

 

[DieselE]

30mpg around town, particularly if they're all short trips and the engine does not get a chance to warm up, would not surprise me.

A 320CDI is one hell of a car to use for shopping trips. On a longer run I would expect you to be getting 40mpg +/- 2.

 

[Rory]

The thing that seems to kill the economy of diesel autos is stop/start motoring - an E320 is a big old car to get moving from rest.
As a comparison, my C270CDi auto also only does low 30's when I do a 10 mile round trip into town (and most of that is urban, rather than town).
On a 200 mile steady motorway run at 70ish it'll show 48MPG. I find it takes about 40 miles from cold for the fuel consumption to settle down (or up!).

My solution is to use my wife's Jazz for local use whenever possible.

 

[Homer]

Hi All

Thanks for your input, maybe I was expecting too much i.e 400 miles plus around town. We did take it on a longer run and it was better than local driving.

I guess if you are not doing alot of mileage, the legendary Mercedes fuel gauge (moves a digit everytime you stop start the car) still applies!!!

One other thing is the A/C, some people say that you should leave it on and others say you can switch it off..any ideas (I usually switch it off if not needed)

Any tips would be appreciated.

 

[Rory]

One other thing is the A/C, some people say that you should leave it on and others say you can switch it off..any ideas (I usually switch it off if not needed)

This has been much discussed - from a fuel consumption point of view, the difference will be negligible.

Many people leave it on all the time. I only use mine when needed, but apparently (and I try to do this) you should use it for 20-30 mins per wk all year round to stop the seals in the system from drying out. I also always try to remember to turn off my a/c a few mins from home, so that they system dries out and isn't left damp for smelly bacteria to breed in.

 

[Rose Chap]

I found the same in the turbo dieseasel Golf I had before I bought the CLK. I never got anywhere near the claimed economy of 50 odd mpg and on average I was getting high 30s on motorway runs and early 30s around town.

I never pussy footed around in it and always made full use of the turbo, but even so I was disappointed in the lack of economy, not to mention the chug chug noise of the engine and the torque steer when accelerating and the blunt nature of the way the turbo came in.

I hope you manage to eke a bit more mileage out of the gallon, making the diesel choice worthwhile.

 

[Satch]

In town traffic that is roughly what I expect from an E320Cdi. A lot of metal to shift, big engine and an auto. Mine takes at least 10 miles to warm up properly and so short journeys will really murder your fuel economy.

They are long distance machines really and the smaller engines are better suited to long term town work.

A new air filter and dose of injector cleaner might help a bit.

 

[GordonTarling]

I have an E320CDI Estate and the figures you're seeing are about average. On my 8 mile trip to/from work every day, I can JUST squeeze 30mpg out of it if I'm very light-footed. More 'normal' driving produces around 26-28mpg. The best I've seen on a long, mainly motorway, trip is 42mpg. Under similar circumstances, my old Volvo V70 produced 20mpg to/from work (if I was lucky!) and around 29mpg on motorway trips, so I'm very happy with my E320CDI!!

 

[mickeymacs]

As the bodywork rusts away economy may improve as the car gets lighter

 

[Rose Chap]

I left London this morning and drove from Camden to Reading, in rush hour, in my CLK 230 making full use of its supercharger where possible and averaged 27.1 miles per gallon. Pretty good I reckon, especially when you consider what's being written about the 320 CDIs above.

 

[Satch]

Turbo diesels in very rough terms consume 25-30% less fuel than a petrol engine equivalent. Compared to a 3.2 litre petrol engine in similar circumstances it is doing well.

The reason large turbo diesels are designed mostly for long distance work is that the high torque output allows high gearing, which lets a 320Cdi run at a merry clip whilst still within or close to the maximum torque band. That is what boosts the fuel economy at steady speed and enables the shove when required.

So it is horses for courses. At the extremes

Trolling around in urban traffic with good mpg but patience required for long hauls =small capacity manual non-turbo diesel

Continental touring abilty with good pace and reasonable mpg but really not that wonderful mpg in traffic = large capacity auto turbo diesel

You have the latter. Enjoy!

 

[GordonTarling]

Satch - you're SO right! We toured Europe last year in my car and the experience was just superb - 3200 miles in two weeks was a LOT of driving, but I enjoyed every mile! (particularly those at over 100mph!)

 

[Vips]

it doesn't look too good for diesels than. I realise that 320 is a big car, but the figures aren't really impressive. In comparison, I get better mileage from my 220 petrol. Averages 26 in town and 37 on motorways.

 

[Satch]

it doesn't look too good for diesels than. I realise that 320 is a big car, but the figures aren't really impressive. In comparison, I get better mileage from my 220 petrol. Averages 26 in town and 37 on motorways.

Trouble is that diesels have been overmarketed and a general perception has built up that they all turn in amazing mpg. Diesels do have a natural advantage but a large engined diesel car designed mainly as an Autobahn sturm-wagon is never going to be a super economy machine.

Many medium sized petrol engines are capable of 35+mpg on a long run but comparing apples and oranges. Very different:

2.2 litre 4 cylinder petrol engine pushing out 150PS and 210 Nm torque

3.2 litre 6 cylinder turbo diesel engine producing around 200PS and 500 Nm torque.

Maybe better comparison would be with the current 220 CDi's that produce near identical power to the 220 petrol but with about 50% more torque. People on this forum get some very impressive mpg figures from those and they perform well enough.

 

[garystu1965]

Whack in some injector cleaner at your next fill-up.

 

[DieselE]

it doesn't look too good for diesels than. I realise that 320 is a big car, but the figures aren't really impressive. In comparison, I get better mileage from my 220 petrol. Averages 26 in town and 37 on motorways.

If economy is the first thing on your mind then buying a big car like an E Class should be off the agenda all together.

The amazing thing about the E320 CDI when it came out in W210 form was it outperformed the E320 petrol, was more economic and was cheaper to buy new. The same economics held good for the W211 with the diesel being £1k cheaper new. However, the price difference is no longer that good for the latest cars.

What you still get is the overtaking ability of the E500 with the economy of a two litre car.

 

[Chris_J]

My C220 CDi isn't doing much better around town. I've had mine drop to 26mpg on one or two occasions.

 

[jeremytaylor]

Diesels are not as economical as they used to be. The particulate filters on some engines and the extra weight (safety measures, extra equipment, etc.) are to blame.

But at least their emissions are vastly cleaner than they used to be.

 

[hawk20]

You guys just aren't trying!!!!
"After completing the high speed records in Laredo, the three unmodified E320 CDIs were driven from Laredo to Tallahassee in Florida, each covering the 1039 miles on a single tank of fuel. Sport stewards supervised the test, sealed the 80 litre fuel tanks and verified the average consumption of 59.46 mpg at the end of the trip.

http://www.benzworld.org/forums/general-mercedes-benz/1244752-diesel-mercedes-kicks-competition.html

For those who missed it this was directly after the new Merc 3 litre diesels set new world performance records: -
The new Mercedes-Benz V6 CDI diesel engine has marked the start of its career with a string of world records. Fitted in three standard-production E320 CDI models, the cars covered 100,000 km, 50,000 miles (80,467 km) and 100,000 miles (160,934 km) in world-record time, and without any technical problems, at a high-speed circuit in Laredo, Texas. Despite the extreme stresses, the maintenance-free diesel particulate filters held up over the entire distances without any deterioration in performance. The 100,000 mile run was made at an average of 224.823 km/h.
http://www.canadiandriver.com/news/050503-1.htm


Out of interest, I have the 320cdi engine in the 220 series S class. I easily get 36-38 mpg on a run and 26/7 round town. The govt combined figure for the diesel S class is 35mpg. Incredible for a two ton monster that does 150 mph and 0-62 in 7.6 seconds according to Autocar.

On my E class 270cdi I regularly got 44mpg on a run.

It is Europe with all the filters for particulates which is constantly reducing the economy of the diesel just as catalysts did for petrol.