W204 C320 CDI - fuel economy

[breezy]

What is everybody getting on their C320 CDI? Pre Blue Efficiency C350 too, since I think that is the same engine.

Mine seems to be giving me 35 MPG across a commute that I would expect 47 from in my older C270...

[Benmac]

Only had my 350 a few days but after a good mix of driving I'm getting about 35. This has dropped from the 41 that he pious owner had recorded.

[breezy]

I just did 50 miles, 40 miles of which was on the motorway with the cruise control at 70 and 10 miles was clear local and A roads.

36.9 MPG the best that I could get.

Something not quite right I think...

[Nick644]

I have a C300 diesel 4matic Estate, so perhaps 70kgs heavier and I think a slightly detuned engine 231bhp. Had it two years now. On a long run, French Autoroute averaging 130kph, (80mph) with speedtronic cruise, it will hover around 40 mpg. 42-3mpg at 110kph (68mph). In London, purely stop start heavy congestion, around 23mpg at an average speed of 9-10mph. Average long term mpg is early to mid 30's I find.

[rassi]

Mine is also a C300 CDI 4matic (saloon), so with the 231 bhp/540 nm engine and the added drag of 4WD, my last tank with exclusive city use has given 26 mpg. On motorway use/long run, I am at 38-40 mpg at 150 kph cruising.

[breezy]

Thanks for sharing your experince.

I did 32 mpg today on my usual route (this time at a decent speed). Definitely something wrong, there is no way I'm going to see 40 mpg from this car...

Any 320/350 owners able to chime in?

[rassi]

How long have you had the car? What mileage does it have? When was it last serviced (including all filters)? What wheels are on it?

[richardhancock]

Hi breezy,

I have the 320 cdi (the later 224bhp version) in the W203, but the figures shouldn't be a million miles apart.

My daily commute is 55 miles of motorway / fast dual carriageway (A12, M25, M20) and I see 42-44mpg (from the OBC) at NSL ish speeds. Calculated, via spreadsheet, is 38-41mpg over the tank.

Hope this helps a little.

Cheers,
Rich.

[GrandGinge]

For what it is worth, I have a W211 E320 Cdi 2008 (facelift) and I rarely see over 30 mpg even @ 70mph on cruise for a sustained period, currently it is averaging 28.2 mpg over 65% motorway/ dual carriageway and 35% town.

I have tried changing all filters (oil, air etc), fluid change, four wheel alignment, premium diesel/ normal diesel, new tyres (as needed anyway) and none of these appear to have made the slightest bit of difference.

Someone has suggested a faulty MAF sensor, I don't have a clue about what impact this would have but would also welcome any views on why such poor economy, what may be causing it (references to heavy right foot aside!) and any suggestions to improve economy.

[breezy]

rassi said:

How long have you had the car? What mileage does it have? When was it last serviced (including all filters)? What wheels are on it?

The car had a Service B in December and is running 225 fronts and 255 rears at 18".

I got the car last week from an MB dealer...

[breezy]

richardhancock said:

Hi breezy,

I have the 320 cdi (the later 224bhp version) in the W203, but the figures shouldn't be a million miles apart.

My daily commute is 55 miles of motorway / fast dual carriageway (A12, M25, M20) and I see 42-44mpg (from the OBC) at NSL ish speeds. Calculated, via spreadsheet, is 38-41mpg over the tank.

Hope this helps a little.

Cheers,
Rich.

This is pretty much what I was expecting so thanks for getting back. My tank is sitting at ~30 mpg at the moment.