W163 320 - poor mpg - where to start?

[allias]

Afternoon

Could you please give me few pointers as where to start to try to reduce fuel consumtion?

I did few tests recently and I get ~17 in city and ~22 on motorway. Considering that my 320 pertol got "only" 102k miles that seems to be a bit high. I have recently swaped tyres and reduced size (not because of mpg) to Conti and have done service (MB Genuine oil).

I know next point of call would be:
- fuel filter
- spark plugs

Is there anything else to check on those what might bring few miles back? Anything else that would make a difference? Tyre pressure is fine.
I want to plan things to do in one go.

Yes I know removing brick from my shoes is the main thing

 

[gIzzE]

Seriously? What were you expecting to get?


Official figures...

Urban mpg 15.5 mpg
Extra Urban mpg 25.2 mpg
Average mpg 20.5 mpg

You're beating them, so think you're doing well.

 

[V12]

Reduced tyre size? Bad idea...

Good luck beating those figures in a 320 ML.

 

[flango]

Mine did better than that the pile of carp it was, used to just nudge 20mpg if SWMBO used it around town on her commute and if I used it on mine 90% motorway 80 mile commute it was just shy of 26mpg

 

[bobmedley]

I drove two ML320's for 100k miles in total and averaged 22mpg (accurate as I had to keep records for tax reasons, so always calculated brim to brim).

It was a curious engine (a bit like the W164 ML350 I had afterwards) inasmuch that no matter how slowly I drove it never bettered 22 mpg.

Don't know if LPG is advisable, but that is probably the only thing you can do.

 

[gIzzE]

When you say reduced tyre size, what do you mean?

I would go to a 235 width and then make sure it is a the correct rolling radius.

Also, a tyre like the goodyear effcientgrip will give better MPG figures, but not talking a great deal.

Going from 275 to 255 to 235 will probably give you 1mpg more each time, and then a very economical tyre like the efficentgrip another 1mpg.

 

[allias]

Thanks to you all... all that just made me clam about "fuel performace".

I had 275/55-17 and I have gone to 255/65-17 as that what I had as spare set. It feels a big more responsive but that compromized a grip. Still all good as it mostly driven by missis to drop or pick-up kids at nursery.

Knowing my figures are fine I will just continue enjoying it

 

[V12]

Have you checked actual values of MAF and Lambda sensors?
Depending on the year it will have either 2 or 4 lambda sensors.

These sensors can adjust the fuel correction and leave the car running rich without flagging the check engine light.

 

[allias]

V12 - do you know figures I should be looking for?

 

[grober]

Thanks to you all... all that just made me clam about "fuel performace".

I had 275/55-17 and I have gone to 255/65-17 as that what I had as spare set. It feels a big more responsive but that compromized a grip. Still all good as it mostly driven by missis to drop or pick-up kids at nursery.

Knowing my figures are fine I will just continue enjoying it

That tyre change will result in a change in tyre circumference from 2214.59 to 2302.06mm this is a change of 87.47mm or 3.95%. this will mean your mpg figures will be slightly out
Car Bibles : The Wheel and Tyre Bible

 

[Benplym]

I pretty much never went past 16-17 city driving in my w163 270 diesel. It's a huuuuuuge car to shift from a standstill and its a petrol. I'm returning 19 average in the ml280 w164 City driving and that's pretty careful driving.