Mercedes ML / GL 320 fuel consumption

Aug 15, 2017
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Anyone other owners here, able to compare fuel consumption figures please? Get around 25-28 mpg not towing (poor, I know), dropping to around 20-21 if I connect the caravan electrics with the engine switched off (to be expected), to a terrible 16-17 if I connect with the car still running when connecting (weird, I know, but observed too many times to not be anything other than fact).

How does that compare with any other same eninge owners' experiences
 

Damian

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Mar 14, 2005
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Cant help with fuel figures but can say that you should never connect or disconnect the van electrics with the car still running.
 
Aug 15, 2017
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How so? Never had a problem save for the fuel consumption funnies and the car's manual says, without explanation, connect with the engine OFF but disconnect with the engine RUNNING. It also, slightly bizarre, says have all the car doors shut too though I think the later is something to do with the suspension having a mind of its own as regards raising and lowering itself.
 
Mar 14, 2005
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Not specifically related to cars and trailer,s In some cases its vitally important that making connections between items must be done when the systems are powered down, as current surges or voltage spikes can be caused when some things are connected or disconnected.

In some cases when items are turned on they will go through some sort of self checking or setting up, if you then add or take something away, the system does not change its settings so its not necessarily going to work properly.

For that reason it is generally the best accepted process to turn items off before connecting or disconnecting things.

Its a false sense of security to believe that becasue you have not suffered any obvious problem when leaving things active whilst making or breaking connections, you may be placing extra stress on them which can lead to premature failures.
 
Oct 12, 2013
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Engine is always switched off when I connect and disconnect as once when I went to connect my trailer the bulbs on the tail board blew ! :(
 
Mar 13, 2008
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Hi. Are you getting your mpg from filling a full tank or relying on the car’s computer? I have owned a 2008 ml320 and a 2015 ml350. 320 gave 30 solo and 22 towing. The 350 34 solo and 26 towing. Never did the plug/unplug thing, did this with the engine switched off in both cases. Does depend on manner of driving. Could get better figures but the ones quoted are averages. Mike
 

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