What kind of mileage are you getting??
Super Member
Joined: Apr 2008
Posts: 635
Likes: 2
From: Cali
2011 GL450
Yeah! Fortunately my 2002 was the last year of the infamous 7.3L Powerstroke, which I think will go down in history as one of, if not the best diesel engines of all time. I ran a total of 5 of them between my personal and company vehicles, for a total of 700K miles, without a major component failure. It was only rated at 250 HP but it would pull a freight train. 17 MPG was an average. It would actually get 18 or 19 on the highway. When I traded in the Excursion, the used car manager was drooling at the mouth. It didn't even have a door ding. Needless to say, I won on that exchange plus got a decent deal on the GL320.
Banned
Joined: Feb 2008
Posts: 164
Likes: 0
From: Columbus, OH
2008 GL 320 CDI
My 320 CDI has about 2K miles on it and I'm getting about 19 MPG overall, with about 3/4+ city driving. I was getting about 17 MPG earlier in the winter, but it has been improving. On the highway, the trip computer says I'm getting in the 23-24 range, but I've yet to log any serious highway miles.
I fondly remember the $3.34/gallon that diesel was selling at back in February when I bought the GL.
I fondly remember the $3.34/gallon that diesel was selling at back in February when I bought the GL.
Senior Member
Joined: May 2003
Posts: 466
Likes: 0
From: South Florida
05 E500
My 550 is at 16.2 mpg for 5300 miles with an average speed of 29 mph. City 75% and highway 25%.
Another insightful tidbit here:
https://mbworld.org/forums/showpost....17&postcount=9
Senior Member
Joined: Dec 2006
Posts: 405
Likes: 1
From: Scottsdale, AZ
2007 GL320 CDI, 2001 TJ Rockcrawler, 2005 Scoobie STI
For what its worth, I have found that when I do a manual calculation of fuel mileage (i.e. fuel the vehicle at the same pump and stop fueling after two clicks of the nozzle.) the computer is actually under estimating the fuel mileage, sometimes by as much as 2 MPG...
I don't know why it does this, perhaps the mileage calculator is based on some algorithm for an average GL 320 and using all of the sensors to estimate.
I suggest you do a few manual calculations and see if yours does the same. It would be interesting to see if the 450 and 550 are the same or more accurate, or ever perhaps if they are over estimating the actual mileage.
I don't know why it does this, perhaps the mileage calculator is based on some algorithm for an average GL 320 and using all of the sensors to estimate.
I suggest you do a few manual calculations and see if yours does the same. It would be interesting to see if the 450 and 550 are the same or more accurate, or ever perhaps if they are over estimating the actual mileage.
Junior Member
Joined: Jul 2007
Posts: 71
Likes: 0
From: Dallas, TX
GL320 CDI, SL550
With my 320 CDI I am getting 22.5 driving very conservative and am at 24.5 on the highway, if I drive at about 60-62...This keeps the engine at about 2000 rpm which seems to be an efficient spot for it...
Diesel is $4.55 in Dallas and going up by the day
Diesel is $4.55 in Dallas and going up by the day
MBWorld Fanatic!
Joined: Apr 2007
Posts: 1,046
Likes: 1
From: Colorado Rocky Mtns.
'06 A6 & '08 GL550
For what its worth, I have found that when I do a manual calculation of fuel mileage (i.e. fuel the vehicle at the same pump and stop fueling after two clicks of the nozzle.) the computer is actually under estimating the fuel mileage, sometimes by as much as 2 MPG...
I don't know why it does this, perhaps the mileage calculator is based on some algorithm for an average GL 320 and using all of the sensors to estimate.
I suggest you do a few manual calculations and see if yours does the same. It would be interesting to see if the 450 and 550 are the same or more accurate, or ever perhaps if they are over estimating the actual mileage.
I don't know why it does this, perhaps the mileage calculator is based on some algorithm for an average GL 320 and using all of the sensors to estimate.
I suggest you do a few manual calculations and see if yours does the same. It would be interesting to see if the 450 and 550 are the same or more accurate, or ever perhaps if they are over estimating the actual mileage.
I don't remember how much mine was off last fall, but the computer was always underestimating based on my actual calcs. So, I don't even pay attention to the computer anymore.
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Senior Member
Joined: Apr 2004
Posts: 254
Likes: 4
From: N. Illinois, USA
2021 GLS450, 2015 E250BT 4Matic, 2007 GL320CDI, 2005 SLK350, 2001 SLK320
I had an interesting experience on my trip to Arkansas last week. The trip down to AR returned an expected 24+ mpg with avg speed of 70 mph. I filled the tank at a Valero station in Little Rock and immediately saw a 10% to 15% reduction in fuel economy. This continued throughout my stay and on my return trip back north through AR and MO. I filled up my nearly empty tank at a station on the MO/IL border and saw my highway fuel economy immediatley jump from 21.2 to 24.5. Same speeds and same wind conditions as the AR and MO portions of the trip. Just different fuel.
What gives? Did Valero slip some Diesel #1 (kerosene) into the Diesel #2 pump? The GL ran fine. It just returned lousy fuel economy with the Valero diesel fuel.
What gives? Did Valero slip some Diesel #1 (kerosene) into the Diesel #2 pump? The GL ran fine. It just returned lousy fuel economy with the Valero diesel fuel.
MBWorld Fanatic!
Joined: May 2007
Posts: 2,244
Likes: 1
From: Scottsdale, AZ
2004 RX330, 2008 Scion xB, 2001 Honda Insight Hybrid, 2010 Toyot Prius v ATP
STP
PS Not that I have an opinion, just pointing out facts.
Banned
Joined: Feb 2008
Posts: 164
Likes: 0
From: Columbus, OH
2008 GL 320 CDI
I had an interesting experience on my trip to Arkansas last week. The trip down to AR returned an expected 24+ mpg with avg speed of 70 mph. I filled the tank at a Valero station in Little Rock and immediately saw a 10% to 15% reduction in fuel economy. This continued throughout my stay and on my return trip back north through AR and MO. I filled up my nearly empty tank at a station on the MO/IL border and saw my highway fuel economy immediatley jump from 21.2 to 24.5. Same speeds and same wind conditions as the AR and MO portions of the trip. Just different fuel.
What gives? Did Valero slip some Diesel #1 (kerosene) into the Diesel #2 pump? The GL ran fine. It just returned lousy fuel economy with the Valero diesel fuel.
What gives? Did Valero slip some Diesel #1 (kerosene) into the Diesel #2 pump? The GL ran fine. It just returned lousy fuel economy with the Valero diesel fuel.
Apart from any ultra low sulpher mixup, I've often wondered if there are differences in octane levels in diesel fuel from manufacturer to manufacturer. Gasoline purchasers always get several octane options at the pump, we only get one. Is it possible some refiners produce higher octane diesel? Unfortunately, I don't know enough about diesel to know whether an "octane" type rating even applies. Perhaps one of our more knowledgeable forum members can shed some light?
MBWorld Fanatic!
Joined: May 2007
Posts: 2,244
Likes: 1
From: Scottsdale, AZ
2004 RX330, 2008 Scion xB, 2001 Honda Insight Hybrid, 2010 Toyot Prius v ATP
Diesel has an octane number of about 15-25. The reason for this seemingly terrible number compared to the ones we're used to from gasoline is the fact that diesel is combusted in a totally different type of engine. Diesel has low volatility, low knock resistance, yet high energy per volume. Because of its low knock resistance, diesel should not be used in a gasoline engine as it will destroy it very quickly and efficiently.
Generally speaking, diesel fuel ignition quality is not measured in octanes, as these are a unit for gasoline. A similar reference value, but for diesel, is the cetane rating. The higher the cetane number, the easier the fuel ignites when injected into an engine. The cetane number is determined by an engine test using two reference fuel blends of known cetane numbers. The reference fuels are prepared by blending normal cetane (n-hexadecane), having a value of 100, with heptamethyl nonane, having a value of 15. The higher the cetane rating, the higher the fuel's propensity to knock! Choosing a very high cetane number will not make the car run better, but using a fuel with too low cetane number may prevent the engine from starting or running.
Generally speaking, diesel fuel ignition quality is not measured in octanes, as these are a unit for gasoline. A similar reference value, but for diesel, is the cetane rating. The higher the cetane number, the easier the fuel ignites when injected into an engine. The cetane number is determined by an engine test using two reference fuel blends of known cetane numbers. The reference fuels are prepared by blending normal cetane (n-hexadecane), having a value of 100, with heptamethyl nonane, having a value of 15. The higher the cetane rating, the higher the fuel's propensity to knock! Choosing a very high cetane number will not make the car run better, but using a fuel with too low cetane number may prevent the engine from starting or running.
Senior Member
Joined: Apr 2004
Posts: 254
Likes: 4
From: N. Illinois, USA
2021 GLS450, 2015 E250BT 4Matic, 2007 GL320CDI, 2005 SLK350, 2001 SLK320
While they might not have an answer (and it may be questionable if they even give you one), it might be worth reporting that to MBUSA and asking them why there'd be a difference with diesel pumped out of the ground by a ruthless nationalist socialist dictator?
STP
PS Not that I have an opinion, just pointing out facts.
STP
PS Not that I have an opinion, just pointing out facts.
I never buy from Citgo due to its Venezuelan (i.e. Chavez) ownership, but I'm not aware of any similar associations with Valero.
MBWorld Fanatic!
Joined: May 2007
Posts: 2,244
Likes: 1
From: Scottsdale, AZ
2004 RX330, 2008 Scion xB, 2001 Honda Insight Hybrid, 2010 Toyot Prius v ATP
See what happens when you become reactionary? <Sheepish> Valero's out of San Antonio. </Sheepish>
STP
Junior Member
Joined: May 2008
Posts: 63
Likes: 0
C220
I was driving the speed limit (30 - 40 mph in town, 60 on the highway). I was trying to take it easy (i.e. no flooring it off the line, etc.) I expect it would do a bit better once broken in.
Last edited by grover432; May 24, 2008 at 08:37 PM.
