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BMW 3-Series (E90 E92) Forum
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how accurate is distance to empty?
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07-19-2012, 09:50 AM | #1 |
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how accurate is distance to empty?
how far have you let the distance to empty run down before you filled up your tank?
turned on my car today, it told me i had 41 miles remaining... the distance from my home to work is about 36 miles. i decided to try to get there and put gas at less than 5 miles remaining... i was a little past halfway to my work, my needle was at the 2nd to the last line before empty when i chickened out and filled up my tank. distance to empty still told me i could have gone at least 25 miles (enough to get me to the gas station near my work place). the bmw chime did not help as it kept on reminding me every so often! |
07-19-2012, 10:12 AM | #6 | |
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Apparently it varies as I once had to ride some 25 miles on my BMW motorcycle with MTE showing "---" during a local temporary gas shortage. The 7 gallon tank took 6.9 gals. when I finally found an open station! Also, as the fuel pump at the bottom of the tank is cooled by gasoline, it's not a good idea to let the level get too low too often. Tom |
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07-19-2012, 10:21 AM | #7 |
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I usually fill up when it says I have about 50 miles left to go but only when I am in town. If I travel I usually don't let it go that low just in case of long distance between stations. Good to know that it will go to 0 miles and still run though.
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07-19-2012, 11:38 AM | #8 |
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It cannot be accurate, why, because it cannot predict the future. It doesn't know what kind of trip you're taking--will you get 19 mpg in the city, 33 mpg on the highway? What would make more sense is for the computer to tell you how many gallons remain. But BMW engineers would consider such an exact number to be too simple, so once again, they overengineered the system...
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07-19-2012, 11:40 AM | #9 | |
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07-19-2012, 11:45 AM | #10 |
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You know what I mean, right? Say the computer were exact, and said you have 3 gallons left. Then, I know I'm going to be stuck in bumper-to-bumper traffic, so I may only have 45 miles to empty. If I'm going on the highway, I'll be able to go about 90-95 miles.
There's no way that the computer can predict 45, or 90-95, it has no clue where you're going. It would be nicer to know how many gals. remain. But I hear you, the avg. math SAT nowadays is probably in the 400's, which is pretty scary! |
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07-19-2012, 11:53 AM | #12 |
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I find it's pretty accurate; I once got down to 4 miles left and the car began to "cough". Long story short I made it to the nearest station and put 15.8 gallons in the 16 gallon tank. I now fill up as soon as I get to the quarter tank line
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07-19-2012, 11:57 AM | #13 | |
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The amount of gas thats in the tank is sent to the computer and the math is done for all of the idiots that dont know their gas mileage, and cannot compute it in their heads. But technically we do have an amount in gallons that is left, the gas gauge tells us. You can put a number on it from the dial with some simple division. TRUE STORY: This has happened twice(both times it just so happened to be girls answering). ME: If your going 60 Miles Per an Hour how many Miles will you travel in one hour. Girl: I dont know I dont want to do the calculations THOUGHT TO SELF WHAT FUCKING CALCULATIONS?!?! ME: It is quite simple listen to the question... If you are going 60 MILES PER ONE HOUR, how many miles will you go in an hour. Girl: I dont know like 90. ME and Girls BF: *LAUGHING OUR ASSES OFF* It was so funny i wrote it down and still have the piece of paper. |
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07-19-2012, 12:06 PM | #15 | |
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I think the entire financial and banking industry in the US "banks" on people not being able to do simple math. It's been my experience that many do not even understand how a loan is amortized, so they've convinced themselves that what a salesman is selling is the way to go. The salesman already did the math for them.... |
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07-19-2012, 12:12 PM | #16 | |
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07-19-2012, 12:14 PM | #17 |
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07-19-2012, 12:15 PM | #18 |
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i do the same; 1/4 left, fill up.
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07-19-2012, 12:44 PM | #19 |
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Does anyone know if it hurts your car to run your gas tank that low?
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07-19-2012, 01:37 PM | #20 |
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07-19-2012, 01:45 PM | #21 |
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Well, it is as "accurate" as one can reasonably expect it to be.
The "distance to empty" is based on the MPG value averaged over some short period of the most recent values (like 5 minutes maybe, or maybe 1 hour, I don't know the exact averaging period). Which means that the estimation will change based on the driving conditions. If you are driving downhill, the "distance to empty" might show 300 miles even for an almost empty tank. But if 5 minutes later the road begins to go uphill, you can run out of fuel in 20 miles. The computer cannot predict the fact that there's an uphill segment ahead, so it will show you the "inaccurate" prediction based on past measurements. The "distance to empty" can only make sense under driving conditions that result in stable engine load and, therefore, stable MPG values. |
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