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I have a 2005 545I and have noticed the miles to empty is going down faster than the odometer is going up in miles. When I manually calculate the MPG it's normally between 20-25 which corresponds to what the car says. When I talked to the dealer they said it was operating correctly and it was a point in time calculation. If that's the case, I still don't understand why the miles to empty is clicking faster than my odometer is going up if I'm getting 20-25 mpg. Am I confused on what information this is displaying? Any thoughts would be welcome.
 

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I believe that 'Miles to empty' fluctuates at any given time as the computer recalculates constantly as it responds to driving conditions (city, highway, speed, accel., idle, etc.), while the odometer is not variable - just a dumb device that measures distance as the wheels turn.
 

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Exactly. It shows you how many miles to empty you have at that current pedal position. For example, if you drove around with the pedal to the floor the whole time (theoretically of course) the number would be way lower than if you were just cruising.
 

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I have only been doing "city driving" the last couple of weeks. I filled up last night and miles to empty was 325. I took a 90 mile trip on highway today and it proceeded to increase as I drove, peaking at 429 miles to empty before it started decreasing again.
 

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I always thought the miles to empty was calculated by the avg. MPG that your computer is showing. Start driving on the HWY for a long distance and your your miles to empty should increase and vice versa.
 

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E60 to E90 to E92
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What you're experiencing is NORMAL. If you read the manual, you'll find that the 'distance to empty' (DTE) readout reflects your driving over the past 20 miles. It does not compute DTE based on throttle position at a given time. Ever notice that after refueling, your DTE might be higher than usual (if doing nothing but highway driving on a roadtrip) vs. lower (nothing but city driving)? It averages your mpg over the past 20 miles, and calculates an estimated range left on your remaining fuel. Therefore, if you're driving nothing but city traffic, or stomping on the pedal for 20 miles straight, your traveling distance in miles will increase (on the odometer) as you'd expect, but your range/DTE will plummet FAST. Drive nothing but freeway from tank to tank, and the DTE will count slower from a higher range. It does not count mile after mile like an odometer would.
 

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Australian 545i
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The distance to empty is continuously recalculated, based on the most recent fuel consumption history. As driving conditions and therefore fuel consumption vary, the distance to empty will also change accordingly. You will notice the distance to empty changing when driving conditions change, for example leaving the city and driving on the highway. However, the distance to empty will stabilise when driving in the same conditions for a period, because the recent fuel consumption history will not change. The distance to empty is a approximate guide only, and doesn't allow for future changes in fuel consumption compared to the recent past.
 
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