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Discussion Starter #1 (Edited)
So my 2011 X5 N63 has not had any excercise for the last three weeks. So I decided to take it for a long spin an an Interstate ,late Saturday night when the traffic was almost non-existent.

I started slowly and after a few miles of sub 60mph, I pushed the X5 to over 100mph; while the road was totally empty of vehicles an weather was perfect.

I noticed that at 100mph , the tacho was only hovering at 2.4k and the mpg needle was just over 12 mpg.

I did these speed bursts about four or five times over a 50 mile stretch of almost straight interstate.

Are these tacho figures and mpg figures correct ?

Why does the N63 revs so low ?

I was expecting it to hit atleast 4k while at 100mph.

Just to clarify again,, the interstate was almost empty late last night :))
 

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So my 2011 X5 N63 has not had any excercise for the last three weeks. So I decided to take it for a long spin an an Interstate ,late Saturday night when the traffic was almost non-existent.

I started slowly and after a few miles of sub 60mph, I pushed the X5 to over 100mph; while the road was totally empty of vehicles an weather was perfect.

I noticed that at 100mph , the tacho was only hovering at 2.4k and the mpg needle was just over 12 mpg.

I did these speed bursts about four or five times over a 50 mile stretch of almost straight interstate.

Are these tacho figures and mpg figures correct ?

Why does the N63 revs so low ?

I was expecting it to hit atleast 4k while at 100mph.

Just to clarify again,, the interstate was almost empty late last night :))

Sounds like your fuel consumption is high...


My 35i sees 100 regularly and at that speed the engine is around 2500 RPMs, and the fuel consumption is in the low 20’s. The superior highway range at high speeds is one of the things that attracts me the most of the X5. C an cross all of Kansas with only one fuel stop doing >90 average.


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Discussion Starter #3
Sounds like your fuel consumption is high...


My 35i sees 100 regularly and at that speed the engine is around 2500 RPMs, and the fuel consumption is in the low 20’s. The superior highway range at high speeds is one of the things that attracts me the most of the X5. C an cross all of Kansas with only one fuel stop doing >90 average.


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Mine is V8 . Is that the reason for the low mpg ?
 

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Mine is V8 . Is that the reason for the low mpg ?

Forgive me for not using the absolute exact technical terms. My understanding is that fuel consumption is purely related to the required horsepower needed to move a vehicle at a certain speed. That requirement will come primarily from the CX (aerodynamic coefficient) and the weight.

Under this premise, the fuel consumption of the V8 and the I6 should be very similar when traveling at the same exact constant speed. There are other factors of course, like wind, incline or tire size, but I am going to assume that those are equivalent between your case and mine.


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Discussion Starter #7
Did you consider trying different speeds to have multiple measurement ranges?


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Yes, up to 85 mph, the needle hovers around 20mpg but as I slowly push it past 90mph and to the 100mph mark, the needle swings down to near 12 mpg.

My V8 mpg gauge range is from 12 to 22
 

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Nuclear engineer
02/2012 X5 35d M57Y CPO 98K miles NOKIAN WR G3 12K miles
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Diesel fuel has a higher volumetric energy density at 35.86 MJ/L (128,700 BTU/US gal) vs. 32.18 MJ/L (115,500 BTU/US gal) for gasoline, Diesel fuel has about 10% higher energy density.

My X5 35d DIESEL has same projected frontal area and shape, so same drag coeficient.

At moderate speed, less than about 60 MPH, I expect to see slightly more than 30 MPG. At immoderate speed, up to 80 MPH, I expect to see about 27 MPG, at 100 MPH I expect about 25 MPG, all instantaneous MPG by Basic Computer.

Aerodynamic drag increases with the square of the speed.

After the quarantine madness was well under weigh I averaged about 80 MPH from central Florida to northern Wisconsin (I-75, I-65, etc.). Where possible the cruise control was set at 80 MPH with long streches at 100 MPH and bursting to 100+ to put poor drivers in my distant rear view where I am safe.
 

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short bursts on an 8 cyl of course 12 is actually Great. I own and have owned many bmw and benz 8 cyls.
 

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Diesel fuel has a higher volumetric energy density at 35.86 MJ/L (128,700 BTU/US gal) vs. 32.18 MJ/L (115,500 BTU/US gal) for gasoline, Diesel fuel has about 10% higher energy density.

My X5 35d DIESEL has same projected frontal area and shape, so same drag coeficient.

At moderate speed, less than about 60 MPH, I expect to see slightly more than 30 MPG. At immoderate speed, up to 80 MPH, I expect to see about 27 MPG, at 100 MPH I expect about 25 MPG, all instantaneous MPG by Basic Computer.

Aerodynamic drag increases with the square of the speed.

After the quarantine madness was well under weigh I averaged about 80 MPH from central Florida to northern Wisconsin (I-75, I-65, etc.). Where possible the cruise control was set at 80 MPH with long streches at 100 MPH and bursting to 100+ to put poor drivers in my distant rear view where I am safe.
And having a 600+ mile tank range while driving it like you stole it comes as a bonus. :) To help put it into perspective, when I drive from Nashua NH to Cocoa Beach FL on vacation, I don't need to stop for fuel until I get down into Virginia. I only need to stop twice for fuel for the entire trip (2nd stop near Savannah GA) and have about a half a tank left when I arrive at my destination.

I am still getting MPG numbers similar to yours in my 2012 X5 35d with only 241k miles on the odometer and still with the original DPF.
 

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Nuclear engineer
02/2012 X5 35d M57Y CPO 98K miles NOKIAN WR G3 12K miles
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And that***8217;s why you***8217;re one of my diesel heroes. I***8217;m chicken to strech a tank to it***8217;s limits. I start looking at a half-tank remaining.

I think it was West Virginia that gave me a real tight anus once with the reserve light on in a strange countryside. For some reason my TDI didn***8217;t make me so chicken, I think IIRC did a 750 gallon tank once. I have only run out of fuel once and that was in the Sixties in a GF***8217;s VW - at the top of a hill above a gas station.
 

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Discussion Starter #13
And that's why you're one of my diesel heroes. I'm chicken to strech a tank to it's limits. I start looking at a half-tank remaining.

I think it was West Virginia that gave me a real tight anus once with the reserve light on in a strange countryside. For some reason my TDI didn't make me so chicken, I think IIRC did a 750 gallon tank once. I have only run out of fuel once and that was in the Sixties in a GF's VW - at the top of a hill above a gas station.
That is my policy too if I am on a long road trip

The only way I am going to run my tank dry is when I have a 5 gallon can of gas in the trunk.
 

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And that's why you're one of my diesel heroes. I'm chicken to strech a tank to it's limits. I start looking at a half-tank remaining.

I think it was West Virginia that gave me a real tight anus once with the reserve light on in a strange countryside. For some reason my TDI didn't make me so chicken, I think IIRC did a 750 gallon tank once. I have only run out of fuel once and that was in the Sixties in a GF's VW - at the top of a hill above a gas station.
LOL I would love to have a 750 gallon tank capacity for diesel storage at home. :)

I don't try to stretch how far I can go on a tank. I'm usually slightly under 1/4 tank when I cross into VA and still have over 150 miles of range left. There are plenty of opportunities to fuel up along the way before it gets critical. I rarely let the remaining range go below 100 miles before I fuel up.

The fuel tank capacity is sized for the gas guzzling models to give them a reasonable tank range. The better fuel economy with the diesel compared to the gassers equates to a longer tank range and this includes the range left when the low fuel warning comes on.
 

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And having a 600+ mile tank range while driving it like you stole it comes as a bonus. :) To help put it into perspective, when I drive from Nashua NH to Cocoa Beach FL on vacation, I don't need to stop for fuel until I get down into Virginia. I only need to stop twice for fuel for the entire trip (2nd stop near Savannah GA) and have about a half a tank left when I arrive at my destination.

I am still getting MPG numbers similar to yours in my 2012 X5 35d with only 241k miles on the odometer and still with the original DPF.

This type of driving (maximizing range) runs in my DNA. We always factored total range among the top purchase decision drivers when getting a new car. My dad has now taken it to the extreme with his last car purchase: He now has a VW Amarok with the 2L 16V Twin Turbo Diesel and added a 135 liter tank in the bed of the pickup - combined he has ~200 liters of diesel, for a highway driving range of ~2800 kilometers. There’s no bladder in this planet that can out-last that.


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This type of driving (maximizing range) runs in my DNA. We always factored total range among the top purchase decision drivers when getting a new car. My dad has now taken it to the extreme with his last car purchase: He now has a VW Amarok with the 2L 16V Twin Turbo Diesel and added a 135 liter tank in the bed of the pickup - combined he has ~200 liters of diesel, for a highway driving range of ~2800 kilometers. There’s no bladder in this planet that can out-last that.


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Geesh. Isn't there a Starbucks closer to his house? :dunno:
 

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02/2012 X5 35d M57Y CPO 98K miles NOKIAN WR G3 12K miles
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200 Liters is only roughly twice my stock fuel capacity. It is far more than my - P - urine void rate (~500 ml is uncomfortable). I will P on a tire roadside - have - bofrore I will $tarbuck$.
 

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200 Liters is only roughly twice my stock fuel capacity. It is far more than my - P - urine void rate (~500 ml is uncomfortable). I will P on a tire roadside - have - bofrore I will $tarbuck$.

They have remarkably clean restrooms at @SBUX in comparison to most public spots...


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02/2012 X5 35d M57Y CPO 98K miles NOKIAN WR G3 12K miles
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Geesh. Isn't there a Starbucks closer to his house? :dunno:

LOL - The cool thing about the place he lives in, is that 90% of roadside restaurants or gas stations on the open road, have a 3-spout La Marzocco... no need for sbux


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