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      07-19-2012, 01:48 PM   #23
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Quote:
Originally Posted by shrink View Post
ive found it to be perfectly accurate.

my 330i once went down to 0miles remaining and it was still going
I don't get how this is accurate then?
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      07-19-2012, 01:51 PM   #24
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Quote:
Originally Posted by RicheyBMW View Post
Does anyone know if it hurts your car to run your gas tank that low?
No one really knows.

It shouldn't hurt a properly designed car. However, there's a popular belief that due to a design error BMW cars should not be allowed to run lower on fuel that 1/4 of a tank. Otherwise, the service life of the fuel pump might get shortened considerably. Some people even claim that BMW service technicians recommend to fill up before it gets lower.

While BMW is indeed infamous for its fuel pump problems (that stretch far beyond "HPFP failure" issue), it is not clear whether this design error has been fixed or not in modern cars.
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      07-19-2012, 01:52 PM   #25
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it adapts to your most current mpg. so if you've been stuck in traffic, it will give you a good estimation of how many miles are left before you run out. same goes if you're on the highway: it's gonna read high enough assuming that you're continuing the same pace.
if you want to know how many gallons are left: WHY NOT LOOK AT THE GAS METER?
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      07-19-2012, 01:58 PM   #26
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Quote:
Originally Posted by darkw1sh View Post

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.
oh were you on tosh bro?
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      07-19-2012, 02:28 PM   #27
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Not my problem. It's not hard to not run out of gas.


Quote:
Originally Posted by Tom K. View Post
And will you personally render emergency assistance any Bimmer driver who runs out of gas due to your advice?

Tom
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      07-19-2012, 02:57 PM   #28
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Quote:
Originally Posted by PR3CI5N View Post
Once the dash says 0 miles left, you still have about 30 mles of driving before you drain your reserve.
I'm not sure this is right. I think the reserve is the part of the tank that's used when the idiot light comes on, not something that kicks in when the needle reads 0. My M3's manual says I have a 13.3-gallon tank plus a 3.3-gallon reserve. When I put gas in immediately when the idiot light came on, it takes....13.3 gallons. The one time I filled it just barely over 0, it took right around 16 gallons.

Quote:
Originally Posted by AndreyT View Post
It shouldn't hurt a properly designed car. However, there's a popular belief that due to a design error BMW cars should not be allowed to run lower on fuel that 1/4 of a tank. Otherwise, the service life of the fuel pump might get shortened considerably. Some people even claim that BMW service technicians recommend to fill up before it gets lower.

While BMW is indeed infamous for its fuel pump problems (that stretch far beyond "HPFP failure" issue), it is not clear whether this design error has been fixed or not in modern cars.
I don't think it's a design error. BMWs have their fuel pumps inside the actual fuel tank, which means that one reason you're not supposed to use the reserve is because the pump relies on being submerged in gasoline to be cooled, so if you're in the reserve and driving hard and/or in a hot climate, then in addition to other potential problems, you risk overheating your fuel pump. That's not so much an error as an inherent property of that design. I don't know enough about fuel pumps to know the advantages of locating the pump inside the tank rather than elsewhere, though I'd bet one of them is not having to have a separate cooling mechanism for it.
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      07-19-2012, 03:01 PM   #29
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Quote:
Originally Posted by JasonDCarton View Post
I've gotten to the point where on the digital dash the Miles till Empty stated "---" . That defiantly freaked me out
i did that yesterday and pumped to the max at 16.05 gal...the user mannual indicated that a 335i fuel capacity is 15.9 gal.
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      07-19-2012, 11:18 PM   #30
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Quote:
Originally Posted by ouchie View Post
I've drove her 40 miles once, and I think I filled her up to 16.5 gallons.
+1

A while back I was traveling back home and had 125 miles left according to the dash. Sadly, this was on thanksgiving weekend and I ended up in a BIG jam on the turnpike. It Lasted about 4 hours and the 1st service area I pulled up to was closed. Got to the point where the dash reading was showing "---" but I ended up making it to the next service area which was exactly 10 miles after the point the miles went blank. Filled up exactly 16.3400 gallons .
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      07-20-2012, 03:34 AM   #31
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A few months ago, my car indicated I could go 20 miles before I'd run out of gas. So I continued on my way towards my destination, which was about 8 miles away. This was the first time in the 4 years I've had my car that I was cutting it that close.

I started climbing a hill that lasted for about 6 miles at 40 mph. I was in third gear (6MT). The reading dropped quickly until I got the dreaded "---" before I reached the top! I feathered the gas, made it over the top of the hill, coasted down the hill in neutral and made it the 2 miles to the gas station with my palms sweating profusely. It took 15.5 gallons. I had 1/2 gallon left.

As others have said, I assume the miles remaining is based on a moving average of recent consumption, with the time window narrowing the closer we get to empty. In my case, I might have been getting 10-12 mpg climbing the hill in 3rd, which is much less than the 25-30 mpg I was getting on the freeway before I got off and started climbing the hill. So the miles remaining didn't apply because the conditions changed dramatically.

I'll never cut it that close again.
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      07-20-2012, 07:13 AM   #32
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The miles until fill up is based on your current gas mileage, and your fuel left in the tank. On multiple occasions I will drive around town and get my mpg's nice and low. Then I'll get on the highway and as I cruise at 75, I actually watch my miles left climb. Is my car creating fuel?!?


Nahh, it's just real time adjusting with your mpg's and fuel left. Pretty cool in my opinion
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      07-20-2012, 07:25 AM   #33
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Quote:
Originally Posted by Sara504 View Post
I never let mine get that low...
+1
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      07-20-2012, 11:58 AM   #34
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Funny story.... I actually ran out of gas in a 328 loaner from the dealership. The dash still said 18 miles left and I had a 14 mile drive to get to the dealership. I had grand visions of coasting into the dealership on fumes, but the car wouldnt start when I went out to it. Had to wait an hour for the flatbed to come. Boy I felt silly after that. Since then I don't trust it at all and consider about 25 miles the critical point to put gas in it.
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      07-20-2012, 12:05 PM   #35
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Quote:
Originally Posted by JasonDCarton View Post
I've gotten to the point where on the digital dash the Miles till Empty stated "---" . That defiantly freaked me out
i got down to the --- before while stuck in highway rush hour traffic. i still went another 1.5 miles on that.
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      07-20-2012, 01:39 PM   #36
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Quote:
Originally Posted by jphughan View Post
I don't think it's a design error. BMWs have their fuel pumps inside the actual fuel tank, which means that one reason you're not supposed to use the reserve is because the pump relies on being submerged in gasoline to be cooled, so if you're in the reserve and driving hard and/or in a hot climate, then in addition to other potential problems, you risk overheating your fuel pump. That's not so much an error as an inherent property of that design. I don't know enough about fuel pumps to know the advantages of locating the pump inside the tank rather than elsewhere, though I'd bet one of them is not having to have a separate cooling mechanism for it.
Virtually all modern cars have fuel pumps inside their tanks. This became the way to do it once cars became fuel-injected. And while it is true that the fuel is indeed used to cool the pump, that is not supposed to mean that you should not let your tank run lower than 1/4. The tanks are designed in such a way, and the fuel gauges are graduated in such a way that when the fuel gauge shows "empty", your fuel tank still has enough fuel remaining to ensure the proper operation of the pump. This is the reason why you can safely run any car to "empty". What is not recommended is to run it beyond "empty". If BMW tanks and gauges designed so that you have to remember to refill every time it gets to 1/4, it is an indisputable design error.

If this is indeed required for proper operation of BMW's fuel pump, then BMW should have stated that the volume of their tanks is not 16 gallons, but rather 12 gallons. And their fuel gauges should have been showing "empty" at the point where they show 1/4 in real life. Stating that "you have 16 gallon fuel tank but you can only use 12 to keep your fuel pump from premature death" is just another way of stating that "we screwed up the design, but we will neither confirm nor deny it officially".
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      07-20-2012, 01:49 PM   #37
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      07-20-2012, 02:49 PM   #38
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I ran mine past zero once. I usually commute and if I'll reach the office or home before I get to zero I'll keep driving.
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      07-20-2012, 03:19 PM   #39
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Every vehicle I've had that gave a "miles-to-empty" reading has seen the --- several times except for the bimmer. They all seem to be on the low side, since I have never ran out of gas. I have gotten down to 10 miles on the e90 I believe.
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      07-20-2012, 04:29 PM   #40
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Quote:
Originally Posted by AndreyT View Post
Virtually all modern cars have fuel pumps inside their tanks. This became the way to do it once cars became fuel-injected. And while it is true that the fuel is indeed used to cool the pump, that is not supposed to mean that you should not let your tank run lower than 1/4. The tanks are designed in such a way, and the fuel gauges are graduated in such a way that when the fuel gauge shows "empty", your fuel tank still has enough fuel remaining to ensure the proper operation of the pump. This is the reason why you can safely run any car to "empty". What is not recommended is to run it beyond "empty". If BMW tanks and gauges designed so that you have to remember to refill every time it gets to 1/4, it is an indisputable design error.

If this is indeed required for proper operation of BMW's fuel pump, then BMW should have stated that the volume of their tanks is not 16 gallons, but rather 12 gallons. And their fuel gauges should have been showing "empty" at the point where they show 1/4 in real life. Stating that "you have 16 gallon fuel tank but you can only use 12 to keep your fuel pump from premature death" is just another way of stating that "we screwed up the design, but we will neither confirm nor deny it officially".
BMW covers this in my '07 3 series manual as follows:

Fuel tank capacity
Approx. 16.1 US gallons/61 liters, including the
reserve capacity of 2.1 US gallons/8 liters.
Refuel as soon as possible once your
cruising range falls below 30 miles/
50 km, otherwise engine functions are not
ensured and damage can occur.<


Like most cars, BMW specs the tank size to include a "reserve" which is purely electrical.

A true reserve on most motorcycles was common years ago when they had gravity fed carbs as the fuel petcock had two openings with the lower one available when one moved the switch to reserve. BMW cyles in th '70's had a petcock on each side with each having a reserve position.

Tom
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      07-20-2012, 05:46 PM   #41
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It's pretty accurate but it's bad to run your tank that low. The pump uses gas to lubricate it. Think about an engine running without oil. Probably wouldn't do it right? Well, similar scenario goes with the fuel pump.
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      07-20-2012, 06:36 PM   #42
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The only possible reason I could see to push a car to a nearly a completely empty tank is say if you're trying to get to a station where it's 2 or 3 cents cheaper than the station you're right in front of. That's when you want to go just a little further on what you have.
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      07-20-2012, 09:42 PM   #43
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Quote:
Originally Posted by PR3CI5N View Post
Once the dash says 0 miles left, you still have about 30 mles of driving before you drain your reserve.
Several times I have pushed that to the limit. That sounds quite unbelievable.

Considering I get the max 31-32 mpg on the freeway depending on traffic and elevation. Under these conditions,computer predicting I am going at about 30 mpg, I have had my car showing 3-5 miles left before I made it to the gas station. AND I'd always end up filling up more than 15.5 gallons, more close to 15.8 in this scenario. And you still think there is one gallon of fuel left to take you another 35 miles? If we believe you have done this before, I can guess that gas is being sucked out of some parts which require constant flow of oil perhaps. I'd never try it and blindly assume I am not compromising anything in the engine.

Once I had my car show '---' for miles remaining, I was in the city, knowing in the next half mile or so I am going to be at my preferred Shell station. I filled up close to 15.9 gallons.

Reason I used to do this often?

I was trying out different brands and only wanted to run compete full tanks with no mixes of one of two for trial runs. All premium gas though.
Do not risk your life or peace of mind by trying to drive like 35 miles on a supposedly empty tank, that would be just plain stupid.


And what Tom said in post #40. Looks like when the Fuel warning comes on, you are already into reserve.
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      07-21-2012, 12:44 AM   #44
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Quote:
Originally Posted by RicheyBMW View Post
Does anyone know if it hurts your car to run your gas tank that low?
Yes it can. there can be small particles settling on the bottom of the tank of your car over time because no gasoline can be absolutely "pure." If you go too low on your tank then some of those particles can enter the pipes and into the engine and clog the system. ouch!
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