M-Class (W164) Produced 2006-2011: ML280CDI, ML320CDI, ML420CDI, ML350, ML500, ML550

ML350 Bluetec Computer MPG vs Real MPG

Thread Tools
 
Search this Thread
 
Rate Thread
 
Old 03-21-2011, 09:16 PM
  #1  
Member
Thread Starter
 
davatk's Avatar
 
Join Date: Feb 2008
Posts: 93
Likes: 0
Received 0 Likes on 0 Posts
2019 GLC 300
ML350 Bluetec Computer MPG vs Real MPG

Has anyone noticed a significant variance in the computer calculted MPG vs the old divide the mileage by the gallons method ? I got about a 3 MPG differece on my last tank and I am almost certain I had it topped off both times. Of course the computer calculated mileage is always the higher one....

Last edited by davatk; 03-21-2011 at 09:27 PM.
Old 03-21-2011, 09:20 PM
  #2  
Member
 
Vernl's Avatar
 
Join Date: Mar 2008
Posts: 207
Likes: 0
Received 1 Like on 1 Post
ML320CDI 2008 all options inc air suspension
Mine has always been almost exact and thats over a 3 yr period
Old 03-22-2011, 08:21 AM
  #3  
Newbie
 
boiler1991's Avatar
 
Join Date: Dec 2009
Location: Kentucky
Posts: 8
Likes: 0
Received 0 Likes on 0 Posts
2009 ML320 Bluetec
Mine is always off by 2-3 mpg. Computer reads higher.
Old 03-22-2011, 02:50 PM
  #4  
Junior Member
 
jralstondr's Avatar
 
Join Date: Nov 2010
Posts: 31
Likes: 0
Received 0 Likes on 0 Posts
2011 350 Blue Tec, 2008 ML 320 CDI, 2004 SL55 AMG
80000 miles on ml 320 cdi 2008 computer mpg reading has always been correct.
Old 03-22-2011, 07:59 PM
  #5  
Member
Thread Starter
 
davatk's Avatar
 
Join Date: Feb 2008
Posts: 93
Likes: 0
Received 0 Likes on 0 Posts
2019 GLC 300
Originally Posted by davatk
Has anyone noticed a significant variance in the computer calculted MPG vs the old divide the mileage by the gallons method ? I got about a 3 MPG differece on my last tank and I am almost certain I had it topped off both times. Of course the computer calculated mileage is always the higher one....
Perhaps I should ask what is the best way to check it. I typically top the tank off until it won't hold any more at all. I know some just go to the first click on the dispenser. Not sure what is the best and most accurate.
Old 03-22-2011, 09:30 PM
  #6  
Member
 
gforaker's Avatar
 
Join Date: Jan 2011
Location: Doylestown, OH
Posts: 199
Received 16 Likes on 16 Posts
2015 Audi S4, 1982 Fiat Spyder, 2010 R350, 2013 E550 Cabriolet
Shouldn't make any difference how you top up the tank as long as it is consistent each time. I always reset the trip odometer each fill up so it is an easy calculation.
Old 03-23-2011, 09:27 AM
  #7  
Member
Thread Starter
 
davatk's Avatar
 
Join Date: Feb 2008
Posts: 93
Likes: 0
Received 0 Likes on 0 Posts
2019 GLC 300
Originally Posted by gforaker
Shouldn't make any difference how you top up the tank as long as it is consistent each time. I always reset the trip odometer each fill up so it is an easy calculation.
Yea, only thing is I filled up (and topped off) at 2 different service stations. Sometimes the slope of the pumps can make a bit of difference, as well as the "foaminess" of the fuel. It may just be simpler and more accurate to make sure you set the fill rate at the same speed each time and go to the "first shutoff" and leave it at that when checking mpg manually. Topping off diesel is a pain...
Old 03-26-2011, 11:14 PM
  #8  
Member
Thread Starter
 
davatk's Avatar
 
Join Date: Feb 2008
Posts: 93
Likes: 0
Received 0 Likes on 0 Posts
2019 GLC 300
Well, I checked it again filling up at the same pump and topping off to the top of the filler neck again. Still off about 2.3 mpg. (28 on computer, 25.779 via manual calulation). I'm gonna try it again, but this time just fill to the first click on the nozzle both times and see what I get. If it is that far off it would seem that may be unacceptable for a 60K vehicle. I had a ScanGuage that cost $150 and was very accurate.
Old 03-28-2011, 10:44 AM
  #9  
Senior Member
 
roadrutz's Avatar
 
Join Date: Oct 2008
Location: Kelowna, BC
Posts: 358
Likes: 0
Received 1 Like on 1 Post
'09 ML550
Under my gas filler cap (ML550) there is a sticker that says DO NOT TOP UP. Like that, in caps. Maybe one of the reasons is for accuracy of the computer.
Old 03-28-2011, 11:10 AM
  #10  
Member
 
gforaker's Avatar
 
Join Date: Jan 2011
Location: Doylestown, OH
Posts: 199
Received 16 Likes on 16 Posts
2015 Audi S4, 1982 Fiat Spyder, 2010 R350, 2013 E550 Cabriolet
Originally Posted by roadrutz
Under my gas filler cap (ML550) there is a sticker that says DO NOT TOP UP. Like that, in caps. Maybe one of the reasons is for accuracy of the computer.
All cars say that now. It can overfill and cause extra pollution. It is reccomended by everyone to just fill up until the hose pops shut and then stop.

If you are concerned about variation from each filling, then just track it over 2 or 3 tank fulls. It will average out, but still give a good comparison to the computer if you do not reset it.
Old 03-28-2011, 04:09 PM
  #11  
Member
Thread Starter
 
davatk's Avatar
 
Join Date: Feb 2008
Posts: 93
Likes: 0
Received 0 Likes on 0 Posts
2019 GLC 300
Originally Posted by gforaker
All cars say that now. It can overfill and cause extra pollution. It is reccomended by everyone to just fill up until the hose pops shut and then stop.

If you are concerned about variation from each filling, then just track it over 2 or 3 tank fulls. It will average out, but still give a good comparison to the computer if you do not reset it.
That sounds like a good plan.
Old 04-15-2011, 10:25 PM
  #12  
Member
Thread Starter
 
davatk's Avatar
 
Join Date: Feb 2008
Posts: 93
Likes: 0
Received 0 Likes on 0 Posts
2019 GLC 300
Originally Posted by gforaker
All cars say that now. It can overfill and cause extra pollution. It is reccomended by everyone to just fill up until the hose pops shut and then stop.

If you are concerned about variation from each filling, then just track it over 2 or 3 tank fulls. It will average out, but still give a good comparison to the computer if you do not reset it.
Well, I checked it again, both times just waited till the hose popped. Computer read 29.2 MPG. Real world calculation 26 MPG. What gives ?

Anyone know if there is any way to calibrate this ? Or possibly a software update ? I had a $150 scan guage once that was much more accurate than this.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 


You have already rated this thread Rating: Thread Rating: 0 votes,  average.

Quick Reply: ML350 Bluetec Computer MPG vs Real MPG



All times are GMT -4. The time now is 07:18 PM.