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Re: About 540i6 fuel economy
BMW BMW General Discussions (alt.autos.bmw)
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#1
 
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Re: About 540i6 fuel economy -
07-23-2003
, 05:21 PM
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Somehow, I'm inclined to blame the low mileage on MTBE additive, but, like I said, I don't know if they do add it to the gas in Flagstaff or not. |
mpg (29 to 24). That's over 15%. Just adding MTBE will usually drop the
calorie content of gas by 2-3%. However, I think AZ might be supplied by
California refineries, and if Phoenix is getting CA standard
reformulated gasoline, then you might see a loss of 10% (2.5 or so MPG).
Going from a higher to lower elevation usually improves fuel economy,
but it seems like you did the opposite.
Thing is, though, anybody ever getting close to 30 mpg from a BMW V-8
seems highly implausible. It might have something to do with the way the
computer varies the mixture at high altitude.
bp
#2
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For a long time, I though that about 24MPG is as good as it gets for 540i 6-speed. Until last week. I decided to take a trip from Phoenix to Grand Canyon. Started with half-full tank of gas, drove up to Flagstaff, refueled there, making a note of modest 21MPG consumption (all right, it's uphill). Then the fun started. By the time I got back to Flagstaff, the gas mileage rose to whooping 29.7MPG. Mind you, I wasn't babying the car, the road was ups and downs all the way, overtakes were frequent, speed was, ahem, reasonable and prudent  Same thing continued as I was driving backdownhill to Phoenix, and of course, the MPG started to fall as soon as I resumed normal city driving pattern. As a result, I made 456 miles on a tank with the average MPG of 26.1. I don't remember ever making more than 400 miles on a single tank of gas, ever. 360 would be more like it. All highway. There are several factors that may have contributed to this: - Do they add MTBE to the gas in Flagstaff? - It was 110F down, 75F up - Elevation changes from 0 to 8000ft Somehow, I'm inclined to blame the low mileage on MTBE additive, but, like I said, I don't know if they do add it to the gas in Flagstaff or not. I'd appreciate insights into this mystery... |
gasoline, so yes, whenever either of these two oxygenates is added to the
gas, your mileage goes down as the computer compensates for the lower HC
content. (The wackos still cannot figure out how the oxygen sensor works
in the exhaust of all modern fuel injected cars)
I have always gotten a significant change in mileage like this when
changing to Arizona or Nevada gas from California gas. Since you were
entirely in Arizona, it seems like some of the change must be that Phoenix
is heavily "doped" gas, and out in rural Az it's not. Not unusual to have
regional variations like this. Then probably significant improvement with
the cooler weather up in Flagstaff, and north to the Grand Canyon. Also,
with that big engine, where others (like me with my "little" 170 cu in
328) note significant loss of power at 8000 feet, you probably just ended
up tapping reserve power while you merrily drove along not noticing any
difference -
Wider throttle opening decreases pumping losses etc. andincreases overall mechanical efficiency of your engine. So it all works
together.
Just my guesses. It's really pretty up there in Northern Arizona, isn't
it?
Frank
#3
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For a long time, I though that about 24MPG is as good as it gets for 540i 6-speed. Until last week. I decided to take a trip from Phoenix to Grand Canyon. Started with half-full tank of gas, drove up to Flagstaff, refueled there, making a note of modest 21MPG consumption (all right, it's uphill). Then the fun started. By the time I got back to Flagstaff, the gas mileage rose to whooping 29.7MPG. Mind you, I wasn't babying the car, the road was ups and downs all the way, overtakes were frequent, speed was, ahem, reasonable and prudent Same thing continued as I was driving backdownhill to Phoenix, and of course, the MPG started to fall as soon as I resumed normal city driving pattern. As a result, I made 456 miles on a tank with the average MPG of 26.1. I don't remember ever making more than 400 miles on a single tank of gas, ever. 360 would be more like it. All highway. There are several factors that may have contributed to this: - Do they add MTBE to the gas in Flagstaff? - It was 110F down, 75F up - Elevation changes from 0 to 8000ft Somehow, I'm inclined to blame the low mileage on MTBE additive, but, like I said, I don't know if they do add it to the gas in Flagstaff or not. I'd appreciate insights into this mystery... |
#4
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For a long time, I though that about 24MPG is as good as it gets for 540i 6-speed. Until last week. I decided to take a trip from Phoenix to Grand Canyon. Started with half-full tank of gas, drove up to Flagstaff, refueled there, making a note of modest 21MPG consumption (all right, it's uphill). Then the fun started. By the time I got back to Flagstaff, the gas mileage rose to whooping 29.7MPG. Mind you, I wasn't babying the car, the road was ups and downs all the way, overtakes were frequent, speed was, ahem, reasonable and prudent Same thing continued as I was driving backdownhill to Phoenix, and of course, the MPG started to fall as soon as I resumed normal city driving pattern. As a result, I made 456 miles on a tank with the average MPG of 26.1. I don't remember ever making more than 400 miles on a single tank of gas, ever. 360 would be more like it. All highway. There are several factors that may have contributed to this: - Do they add MTBE to the gas in Flagstaff? - It was 110F down, 75F up - Elevation changes from 0 to 8000ft Somehow, I'm inclined to blame the low mileage on MTBE additive, but, like I said, I don't know if they do add it to the gas in Flagstaff or not. I'd appreciate insights into this mystery... |
#5
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I have always gotten a significant change in mileage like this when changing to Arizona or Nevada gas from California gas. Since you were entirely in Arizona, it seems like some of the change must be that Phoenix is heavily "doped" gas, and out in rural Az it's not. Not unusual to have regional variations like this. Then probably significant improvement with the cooler weather up in Flagstaff, and north to the Grand Canyon. Also, with that big engine, where others (like me with my "little" 170 cu in 328) note significant loss of power at 8000 feet, you probably just ended up tapping reserve power while you merrily drove along not noticing any difference - |
was driving my other car up there - 2L four banger... Modern Honda
engine, though, maybe it was smart enough, or, again, there was a
power reserve. No stats, though, 'cause there's no computer in that
one.
Quote:
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It's really pretty up there in Northern Arizona, isn't it? |
as if you can touch the sky. When you drive I-17 southbound from
Flagstaff, it feels as if Need For Speed Hot Pursuit suddenly came to
life and animated Rocky Pass just for you, if you know what I mean
When you drive northbound AZ89A to Gerome, you're having the time of
your life...
#6
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Raybender <raybender (AT) NOSPAMCovad (DOT) net> wrote I have always gotten a significant change in mileage like this when changing to Arizona or Nevada gas from California gas. Since you were entirely in Arizona, it seems like some of the change must be that Phoenix is heavily "doped" gas, and out in rural Az it's not. Not unusual to have regional variations like this. Then probably significant improvement with the cooler weather up in Flagstaff, and north to the Grand Canyon. Also, with that big engine, where others (like me with my "little" 170 cu in 328) note significant loss of power at 8000 feet, you probably just ended up tapping reserve power while you merrily drove along not noticing any difference - Indeed, no difference. On the other hand, not that I felt one when I was driving my other car up there - 2L four banger... Modern Honda engine, though, maybe it was smart enough, or, again, there was a power reserve. No stats, though, 'cause there's no computer in that one. It's really pretty up there in Northern Arizona, isn't it? Absolutely stunning. When you stop on I-40 east of Flagstaff, it feels as if you can touch the sky. When you drive I-17 southbound from Flagstaff, it feels as if Need For Speed Hot Pursuit suddenly came to life and animated Rocky Pass just for you, if you know what I mean When you drive northbound AZ89A to Gerome, you're having the time of your life... |
believe that you are still about 1100 feet above sea level in Phoenix, but
it is a far cry from the 7,000 to 9,000 in the Flagstaff area. If you have
the time, you might head east from Flagstaff to Holbrook and then south via
180 & 191 to explore the White Mountains. The stretch from Springerville
down to Morenci offers great roads & stunning scenery.
Tom
#7
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I have a 99 540 6 speed and routinely get 27-29MPG highway driving 75-85MPH. |
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