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Fuel gauge -- how low can I safely go??

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I'm trying to surpass the 450km mark for the first time ever on one tank of diesel. I'm at about 410kms with 3.5L flashing. How low can I go before I need to gas up?? I don't want to cause any damage to the car, so I don't want to push things too far.

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When I filled my first tank, I let it get to 0.0, just and was no problemo, took 22.0 litres, and from what I've read on other threads, people seem to routinely do this.

Last tank was 425 with 3.0 on guage, but it still only took 18 litres, so the math isn't perfect and seems to err on the side of safety.

If you're shooting for 450, go for it you're going to get there with most of a gallon remaining, you'd probably be good all the way to 475 I bet.

NB

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I'm trying to surpass the 450km mark for the first time ever on one tank of diesel. I'm at about 410kms with 3.5L flashing. How low can I go before I need to gas up?? I don't want to cause any damage to the car, so I don't want to push things too far.

When you hit "0.0" you still have 2L remaining in the reserve.

And your right. If you put gas in your car you will danage it. Put diesel in instead. :cheeky:

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Check out my listing at http://www.spritmonitor.de/en/ under user id "smart65". I frequently go past 500 km on a tank. As long as you have a station that you know for sure will be open and has diesel fuel, you can safely run it to 0.0 (according to eddie*3), but I usually chicken out at about 1.0 litre. I figure 3.5 litres could carry you about 88km if you are driving for economy (using 25 km/litre as a rough guide). For MOST fillings in my list, you can calculate how many litres I had left, by subtracting the amount from 22. A while back, I used a pump that always indicated more fuel dispensed than it actually delivered. The pump at the station that I now use, consistently delivers fuel in amounts that correspond (within a half litre) with the known factors (tank size: 22 litres and litres-remaining, from the LCD dashboard display). By the way, my usage is almost all highway, and lately I've been attempting to stay at or below 90 km/hr. On superhighways, this means driving only in the right lane. At that speed, merging traffic can accelerate to get in front or drop in behind, until a chance to pass presents itself. It's actually quite relaxing. There are usually a few trucks that travel at 90. Some say 100 km/hr on superhighways is too slow, but I find it's o/k, except in congested fast-moving traffic, where I may become a roadblock. In that instance, I pick up the pace.

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Wow, the spritmonitor is cool!! Much easier than trying to figure out the math myself :D

There's a 24-hour station that sells diesel close to our house, so I'm pretty confident that I can gas up any time I need to :) Well, OK, DIESEL up!! :cheeky:

I really don't drive for economy -- I did for one tank, but I found that the mileage was pretty much the same as when I drive normally. Meaning, on average about 10kms/h over the speed limit :puppy: I shift at around 2500 RPMs, and downshift when I approach a red light or stop sign. So I don't think I'm being TOO rough on our smart :)

I've never been clear on the reserve amount -- so it's a 22L tank plus 2L reserve then?? So when the 5L warning starts to flash, that means I've used 17 litres.

I may chicken out when I reach 450kms, but maybe I'll try for 475kms!!

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That's right...

The 5 blobs represent 3.4L each totalling 17 out of our 22 litres... But they don't get accurate until we the second to third blob disappears...

At 0.0L you have 2L left and it would be STRONGLY recommended you fillup. Not that I'm one to follow recommendations... :P

2.0L should get you 40km. I've taken it to 85km before I blew dry (which fills up 24.1L to the lip)...

It is a 22L tank including a 5L reserve. The hidden 2L is for us numbskulls who like to push the limits a little further... Which is dangerous for our fuel pump (which is both lubricated AND cooled by diesel)...

Eddie

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Whew!!!! Just dieseled up with 0.0L and 466kms showing on the display!! I put in $22.32 -- although those 32 cents worth ended up on the ground, because I got distracted by a guy who was asking me about our smart. Oops!!!!

So I can get over 450kms on one tank -- but I won't push it to the limit again!! It's too scary seeing the 0.0L flashing!! :oh:

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So let me get this straight... we actually have a 24 litre take including the "hidden 2 litres"? Where did you guys hear about the 2 remaining litres?? I've never heard of that, I'm surprised. And i never get over 400Km/tank. Usually just around 350km.. does that mean i drive too fast or could something be wrong with my smart?

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Well on a consistent basis I fillup 22.5 - 23.5 litres of diesel.

A reliable source told Mike T about it, who told me...

Who tried to take advantage of it... And so far blown dry once (filling 24.1L the next morning)...

But again, even though I do... I definately DO NOT recommend going past the 0.0L mark on the LCD...

Eddie

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The 5 litre countdown is the reserve. You are supposed to fill up at the earliest opportunity when you see this.

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So far I don't think there have been ANY poor fuel economy numbers attributed to something being "wrong" with the smart itself. The capability is there on all cars...

There may be a difference in here between the regular drivers and the "fanatics" (Cheers! Eddie3) but don't lose sight of the fact that no matter how "crappy" you perceive your numbers to be .....you are still beating everything else on the road today!

Its consistency that regularly gets the extremely good numbers. You cannot drive it nicely one trip then mat it the next one and expect it to average out.

My average is 4.2 and most of that is in town driving. I am very happy with that number considering the town drive and my driving habits. Even though it may not be great compared to otheres it is a far cry better than the 10.2 on my MPV!

S

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So let me get this straight... we actually have a 24 litre take including the "hidden 2 litres"?

Nobody knows for certain, but here's my best guess. :BlahBlah:

o The tank itself is 22Litres (to some standard, I'm sure)

o The filler neck holds ~1-2 L, depending on how far you fill it

o The pump cooling/separator holds ~1-2 L

The tankage claimed by smart is 22L which includes the 5.0L reserve, the rest is incidental and variable from person to person. But it does appear to be accessible to the fuel system.

At least that's how I sees it. YMMV. :cheeky::2cents:

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The diesel fuel pump uses fuel for cooling, and there is a water/fuel separator filter. I believe they are integrated and housed under the car.

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2.0L should get you 40km. I've taken it to 85km before I blew dry (which fills up 24.1L to the lip)...

I have filled over 25 litres without having blown dry. So there are some potential 'air pocket' characteristics of the tank, and it may have to do with filling on a sharp decline whther you squeeze more than 24 L in.

The bottom line is why wait for 0.0 to flash? It's needless grief. Just know that when it does, you have maybe 40 km to get diesel, or you face possible repairs.

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The angle the car is siting at doesn't have any impact on the amount of fuel you can fit in per fill.

-Iain

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The angle the car is siting at doesn't have any impact on the amount of fuel you can fit in per fill.

-Iain

Are you sure about that?? When we were in Guelph before the Niagara cruise, we filled up at a Sunoco station. Our car was on a pretty steep incline, nose end down. The guy put in more diesel than the indicator showed would fit. We got over 250kms on the first 2 blobs, which NEVER happened before or since.

The only explanation we could come up with for the apparent filled-beyond-capacity tank was that we had been parked on an inclince. Or else the Sunoco station in Guelph has the best diesel anywhere!!

smartzuuk, I usually fill up way before 0.0L is flashing. But I just wanted to see how far I could go on that tank, seeing as our mileage seems to be improving lately. You're right, seeing the 0.0L is WAY too stressful!! I won't be doing that again any time soon!!

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If someone else filled it, how can you use that as a baseline?

The thing is, the tank is always below the nozzle opening. The opening is always the highest point in the fuel storage system, including any of the piping until the fuel pump. No matter what angle you tip the car at (within reason, obviously - turn the car upside down and this doesn't apply), the opening is always the highest point and the fuel will fill up.

It's like, holding a beer bottle. Tip it 45 degrees in any direction, it won't spill out. You know what I mean?

-Iain

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No, because the tank is not like a beer bottle.

I believe (based on where the tank is situated), that with the front of the car facing down, you will actually fill more, and others have noted the same.

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Wow! Then the laws of physics are bending just for you ;)

Sorry, but until I see someone cut away the side of the car and show me how mysterously it's possible to make diesel flow uphill, it doesn't make any difference.

The fueling opening is the highest point in the fuel system. If you fill up and can see fuel there, you've filled to the absolute maximum capacity, regardless of orientation, end of story.

-Iain

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Not really.

The nose down, car leaning to driver's side attitude will ensure that all of the air pockets in the tank are evacuated on a fill. You cannot compare the complex shape of the smart fuel tank, or its filler hose arrangement, to a beer bottle!

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Whatever... trying to dispute physics is like trying to milk a rock.

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Just a few ideas, pardon the crude graphics, and no flaming accepted because I herefortwo declare that I'm talkin' outa my arse...

If the tank is as described in #1, Duck would be correct

If the tank is as described in #2, Duck would be incorrect, as shown in #3.

If the tank is as in #4, with an air bleed line that connects to the filler tube, then it would be possible that even though the tank appears full, it will slowly bleed off air, and then equalize, leaving head room again, which would explain an earlier post about lots of room after a very short drive, while still holding true on #3...

Just a thought or 4 from the captains porthole!

NB

post-827-1152733721.jpg

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Thanks for the graphics CNB!

#1 could be complicated by the filler tube actually entering into the tank (extending to the bottom) and also, given the flat nature of the tank, if the tube enters at one side or one corner, the attitude of the vehicle would very much determine how much fuel would get in.

Duck, you neet to let smartzuuk or I fill your tank, you'll see....

Doesn't anyone remember what a smart fuel tank looks like? It's not a simple 22 L cube.....

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Duck, you neet to let smartzuuk or I fill your tank, you'll see....

So what, now I'm filling my tank wrong? What will I see? That there's no magic involved here?

:steamed:

-Iain

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