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Maxwell Smart
Date registered: Dec 1899
Location:
Vehicle(s):
| Fuel Consumption?
I know that the estimated fuel consumption figures are under ideal estimates but just how different should one expect them to be from reality.
The official metric figures for my G are
City: 14.6
Highway 10.6
Combined: 12.1
In reality I am getting about
City: ~20+
Highway: ~17-18 at 130 km/h ~15 (maybe less depending on wind) at 100km/h
Combined: ~16
I can understand the City being way off living in London but the Highway being 50-70% off?!?
Just wondering if such discrepancies are normal or is something possibly not running right/need changing. I am fairly certain though not positive that when Bill and I drove back from Germany we were getting around ~15 l/100km and driving 130-160km/h. |
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DUTCH
Administrator Doppelgänger
Date registered: Apr 2006
Location: US, GA, Atlanta
Vehicle(s): 2015 Audi Q7 3.0 TDI,2018 Sprinter
Posts: 9963
| RE: Fuel Consumption?
My experience with my G500 is that above 65 mph, the fuel consumption drops like a stone. |
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Maxwell Smart
Date registered: Dec 1899
Location:
Vehicle(s):
| RE: Fuel Consumption?
DUTCH - 3/12/2007 11:02 AM
My experience with my G500 is that above 65 mph, the fuel consumption drops like a stone.
That's about 100km/h. I'm still running about 50% higher than estimated consumption at that speed which to me seems a lot? I think at 80km/h (50mph) I can get it down to around 12.5-13 l/100km but that is still quite a bit higher than the estimated consumption and in my opinion a lot slower than highway speeds!
PS - Isn't it about 5am in the US right now?  |
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DUTCH
Administrator Doppelgänger
Date registered: Apr 2006
Location: US, GA, Atlanta
Vehicle(s): 2015 Audi Q7 3.0 TDI,2018 Sprinter
Posts: 9963
| RE: Fuel Consumption?
Maxwell Smart - 3/12/2007 6:19 AM
PS - Isn't it about 5am in the US right now? :sleeping:
6AM. We just moved to Daylight Savings Time this past weekend - 3 weeks earlier than normal. Still, I'm up at 5:15AM on weekdays to get the daughter off to her school bus. |
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KERR
Date registered: Dec 1899
Location:
Vehicle(s):
| Re: Fuel Consumption?
with my bigger tires the computer says i get between 8.9-9.5 last week in town.
Then this weekend i ran over to the next city and computer showed 11 mpg
In a nut shell i can got 215-225 miles in town. then about 250-275 on the free way.
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79percent
Extreme Veteran
Date registered: Apr 2006
Location: Remscheid / Germany
Vehicle(s): 300 GE
Posts: 537
| Re: Fuel Consumption?
300GE - 170HP
City: ~16+
Highway: ~15-16 at 130 km/h ~14,5 (maybe less depending on wind) at 100km/h
Combined: ~16 GE 320 - R6 - 211 HP
City: ~18+
Highway: ~17-19 at 130 km/h ~16 (maybe less depending on wind) at 100km/h
Combined: ~17 everything in Summer with normal tires (no AT or MT) |
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Maxwell Smart
Date registered: Dec 1899
Location:
Vehicle(s):
| Re: Fuel Consumption?
Eep! That mean's that Klaus is getting better mileage in a petrol G than I do in a diesel G! Something is not right..... 
What can affect the mileage so much? I've Dueller tires so I don't think that they are the cause. |
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79percent
Extreme Veteran
Date registered: Apr 2006
Location: Remscheid / Germany
Vehicle(s): 300 GE
Posts: 537
| Re: Fuel Consumption?
Maxwell Smart - 3/12/2007 5:48 PM Eep! That mean's that Klaus is getting better mileage in a petrol G than I do in a diesel G! Something is not right..... What can affect the mileage so much? I've Dueller tires so I don't think that they are the cause. Did you adjust your speedo? Just in case you have a different size mounted! |
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Fenalaar
Elite Veteran
Date registered: May 2006
Location: Narvik, Norway
Vehicle(s): 2001 ML270CDI, Polaris 400L Big Boss
Posts: 826
| Re: Fuel Consumption?
First off - are the figures you're quoting coming from the driving computer, or are the real, measured values ?
Fill the car all up, drive a known distance (i.e. not measured by the odometer) and fill up again at the same pump. Then you can calculate the real figures.
You can affect the consumption a lot by your driving style. I find my '86 300GD (with turbo) is the most economical at around 70km/h. If I drive around 20km/h faster than the speed limit (i.e. speeds up to 110-115 km/hfor long distances), I can almost double the consumption, compared to going just a little under the speed limits...
Also, an Italian tune-up now and then will help the engine running better. I'm not sure if it really helps consumption, though, since the tune-up itself will eat a lot of fuel...
The so-called highway figure does not really mean highway speeds as you consider them. The figure means consumption during steady driving at 80km/h. A better expression is "extra-urban consumption" - not implying highway speeds.
How agressive is your driving style ? 20+L/100km is a bit high for city driving, but it's easy getting those figures with an "on/off" driving style. Full throttle from each stop and then full brakes in front of each zebra crossing/red light is nice for the gas station owners, but not nice for your wallet.
Around 15L/100km sounds about right for city figures if you're a bit careful. When driving around the city, I almost never use the brakes, except for keeping the car staitionary while still in gear - some planning ahead, for instance seeing the red light a distance ahead and then allowing the car to slow down by releasing the throttle and rolling along at idle until you either have to stop or you get green light again will save you considerable amounts of fuel. Trying to adapt your schedule to avoid the rush hour and the worst places for congestion also helps.
I get around 10-11L/100km extra-urban on mine. I haven't measured city consumption figures yet, but I'm not sure I want to know... 
Johan-Kr |
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Maxwell Smart
Date registered: Dec 1899
Location:
Vehicle(s):
| Re: Fuel Consumption?
Thanks Fenalaar - I was measuring by the driving computer.
I will try and calculate it manually instead. But I do find I need to fill up every 375-400km or so but only need to fill up every 550-600km in my 300GD.
Though I think that the tank in my G300TD reports empty much sooner than in my 300GD.
I don't drive on/off and while yes 20+ L/100km is high, have you ever driven... er sat still in London traffic... the average speed is ~13.5km/h. About 3km/h slower than it was 100 years ago.... on a bad day it can take me an hour to get 6km. 
Interesting comment about highway speed meaning about 80km/h. I can get the computer down to about 12.5 l/100km at that speed and figure that 20% off is perhaps acceptable due to wind, inclines etc.
Didn't think I needed speedo adjusted for Duellers? |
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Fenalaar
Elite Veteran
Date registered: May 2006
Location: Narvik, Norway
Vehicle(s): 2001 ML270CDI, Polaris 400L Big Boss
Posts: 826
| Re: Fuel Consumption?
Speedo will normally be a bit off anyways.
Now mine is a 460 without all this fancy-scmanzy computer adjustment for different wheel sizes, so the following might not apply to you...
After I had the car in for some maintenance work at an army shop that also does civilian work, my brother took the car back for me (he works there, but not at the car department). He commented that while keeping the to the speed limit he left all the other cars way behind, and thought the speedo must show way to little.
Anyway, I borrowed a GPS and measured the speedo. The car is registered with 235/75R15 as original tyre dimension. With 255/75R15 the speedo matched the GPS with +-1km/h all the way up to 80km/h. Most cars are 5-10km/h below the stated speed at 80km/h.
Johan-Kr |
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mortinson
Expert
Date registered: Apr 2006
Location: Madrid, España
Vehicle(s): '98 G300TD LWB, '98 E300TD Saloon
Posts: 1355
| RE: Fuel Consumption?
Max, I think that you consumption is way too high:
http://www.spritmonitor.de/de/uebersicht/28-Mercedes-Benz/268-G-Kla...
In any case, I would suspect tyre syze. Are your tyres the same size as those fitted when your G was manufactured? If they are not, you have to allow for the same percentage variance as in your consumption calculations.
Cheers |
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Maxwell Smart
Date registered: Dec 1899
Location:
Vehicle(s):
| Re: Fuel Consumption?
I've got no clue if the tyres are the same size or not...
Thanks for the link. Interesting to see Alan's details.
http://www.spritmonitor.de/de/detailansicht/143772.html
Edited by Maxwell Smart 3/13/2007 9:53 AM
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79percent
Extreme Veteran
Date registered: Apr 2006
Location: Remscheid / Germany
Vehicle(s): 300 GE
Posts: 537
| Re: Fuel Consumption?
Max, I compared my Speedometer with an GPS based navigation system (TOMTOM) and figured out, that my G shows 10 Km/h too much when drving at 100km/h. 10% tolerance in speedo will end in 10 % tolerance on the odometer als well. Just check with a navigation system your speed and you'll get a feeling which tolerance you have. RGDS Klaus |
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Maxwell Smart
Date registered: Dec 1899
Location:
Vehicle(s):
| Re: Fuel Consumption?
79percent - 3/13/2007 2:59 PM
Max, I compared my Speedometer with an GPS based navigation system (TOMTOM) and figured out, that my G shows 10 Km/h too much when drving at 100km/h. 10% tolerance in speedo will end in 10 % tolerance on the odometer als well. Just check with a navigation system your speed and you'll get a feeling which tolerance you have. RGDS Klaus
Does that explain why I tripped a speed camera doing 75 in an 80 zone? Have been wanting to get a factory nav system (don't like having all these things stuck to my windshield/dash) but as I don't have one yet....
But looking at Alan's readings I think that I am not that far off of what he is showing. So perhaps it is just inaccurate - but are they really that inaccurate?
Edited by Maxwell Smart 3/13/2007 12:46 PM
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ez rhino
Date registered: Aug 2006
Location: Charlotte, NC
Vehicle(s): 2010 Rubicon Unlimited; 2009 Mini Clubman JCW
| Re: Fuel Consumption?
My 96 G320 with the inline 6 gets 14-15mpg in they city, 18-19mpg on the highway....IF you're nice to it! Now with my wife driving it like a bat out of heck, like somebody said earlier, drops like a stone. |
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j.edwards
Date registered: Dec 1899
Location:
Vehicle(s):
| RE: Fuel Consumption?
We live in the L.A. area and do a lot of freeway miles. Both my wife and I drive hard. The computer shows 13.5 mpg for all types of driving. |
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4x4abc
Date registered: Apr 2006
Location: La Paz, Baja California, Mexico
Vehicle(s): 02 G500
| Re: Fuel Consumption?
Max,
what is your tire size? Bridgestone Desert Dueller - right? Then I can tell you how far you are off. |
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Maxwell Smart
Date registered: Dec 1899
Location:
Vehicle(s):
| Re: Fuel Consumption?
4x4abc - 3/14/2007 3:09 AM
Max,
what is your tire size? Bridgestone Desert Dueller - right? Then I can tell you how far you are off.
Thanks Harald. They are Dueller HT 689s - tire size is 265/70 R16 |
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mortinson
Expert
Date registered: Apr 2006
Location: Madrid, España
Vehicle(s): '98 G300TD LWB, '98 E300TD Saloon
Posts: 1355
| RE: Fuel Consumption?
Well, you are not that far off.
The G300TD was (I believe) factory fitted with 255/65R16 tyres with 737.9 mm of diameter.
Yours are 265/70R16, with 777.4 mm of diameter.
Increase is 5.35%. This means that, in order to more accurately calculate your consumption, you have to increase the distance achieved with a certain amount of litres by 5.35%.
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