When to gas up????

<div class='quotetop'>QUOTE(CdnPrius06 @ Jul 6 2007, 08:00 AM) [snapback]473924[/snapback]</div>

Why are you compelled to push your luck?

Isn't 450 miles per tank enough?

 

<div class='quotetop'>QUOTE(CdnPrius06 @ Jul 6 2007, 09:00 AM) [snapback]473924[/snapback]</div>

I would suggest you fill up as soon as you get to one bar. At some point, the one bar will flash. The Prius will make a beep noise; really easy to miss the sound. I think I heard it once in the 11 months I've had my silver baby.

I wouldn't wait to be flashed. When you get to one bar, find a gas station, and fill up before the blinking.

And I believe the rule is not to top it off. In NJ, we're not allowed to pump our own gas (which is fine by me since I don't want to smell like 87 Octane). Sometimes the attendants give me a hard time and insist on topping in off so they can have an even $ amount. It can get loud. <_<

I also tend to not pass on my credit/debit cards and pay cash at the pump since I've already been burned once with paying for the last guy's gas. :angry:

-D

 

No fuel light per se. The last bar starts flashing and you get a brief beep and "Add fuel" prompt on the MFD. I fill up at my first opportunity after that. If I'm on the road where I'm not sure how long before I can fill up, I'll probably do it before then with one bar.

 

"How far can I go" does not have one fixed answer. It depends on outside temperature, air pressure, and who knows what else. It *is* true that when the last pip starts to flash you will not be able to go much farther.

You really should get a complete copy of the owner's manual, either from a dealer or an online .pdf (perhaps some kind soul can post a link) There's more detail in it than has been transcribed into Priuschat.

 

I usually fill up when the gauge is at 1/2. Based on my highway trips so far, I think my car will go about 900 km on a tank. My overall average is 4.9 l/100 km (45 L tank).

Don't overfill. It can damage the tank. I usually put a little more in after it shuts off (just to be sure it wasn't a false shut off). If I hear fuel in the filler tube I stop! You can hear a change in sound, sort of a gurgling when the fuel reaches the bottom of the filler tube.

Now, I've had my car for 5 weeks now, 4300 km on it so far. I've overfilled it twice, due to nossles not shutting off. So, worrier that I am, I did some calculations. If you fill to the top of the filler neck what are the consequences?

1. Based on 0.1% expansion of gasoline per deg C, a 45 litre tank, underground fuel temp at 15 deg C and air temp at 30 deg C, a full tank will expand 0.5 to 1 litre.

2. You could "burn this off" but it would take me about 20 km to do so. I would suspect the fuel will take some time to warm up and expand, say 30 min. at the soonest. So you'd have to not stop for that long at least.

3. I'm not including air that will be trapped in the tank, which will cool to the fuel temp when you fill up from the evap and fuel splashing, then expand more than the fuel when it warms up. There is always -some- air trapped in any fuel tank even with a bladder. This air will provide some pressure inside the tank when it warms up.

4. The result is some fuel -could- be forced through the evaporative vapour recovery system. I'm told by a very reliable source that the "carbon canister" is small in the Prius, and can easily be filled with fuel. The overflow goes into the space between the bladder and the steel tank. Here it will not escape, and will, over time, corrode the fuel lines, carbon canister, and any other apparatus in there. It's a sealed tank, so if it damages anything, it's new tank time. About $1000. Best to be conservative when filling.

5. What will filling to the top of the filler tube gain you? As it's happened to me twice, I have some estimation of the volume of the extra fuel I got. If I had done it intentionally, I would have accurate figures. I estimate I went an extra 80-100 km before the gauge lost the first pip. That translates into about 4-5 litres of extra fuel. So you -could- actually get a 1000 km tank if you filled to the top of the filler tube. Maybe.

The time estimate for the fuel to reach ambient is based on my previous experience with other cars, watching the fuel expand up the filler tube (car with straight filler tube to the top of the tank).
The fuel expansion rate is from several sources on the internet. I picked ones that looked reliable (papers presented at various conferences).
Underground fuel temp varies over North America. I picked an average value, skewed for Canada. Remarkably, it does not vary a lot with season. The tanks are fairly deep in the ground, at least here in Canada.

 

1) You get down to the last bar
2) The last bar blinks
3) The last bar stops blinking and goes off
4) Pure Prius Roulette at that point.

Note the following events happen One, Two, Three, TOD......really fast.

 

I gas up when any of the following conditions are true:

1) Gas is unusually cheep.

2) I'm in Traverse City and my tank is under half full (we live out in tourist country, so if I don't fill up in the city I can end up paying tourist prices for gas).

3) Any time the gauge is at two bars or under I plan to stop next time it's convenient.

4) A one bar, no matter what the price.

Tom

 

<div class='quotetop'>QUOTE(CdnPrius06 @ Jul 6 2007, 09:27 AM) [snapback]473937[/snapback]</div>

usually can count on going 10 times you average mpg give or take a few.

 

<div class='quotetop'>QUOTE(CdnPrius06 @ Jul 6 2007, 06:00 AM) [snapback]473924[/snapback]</div>

Why bother? Milage isn't the same as miles per tank.

Although you will get ever so slightly better milage as the tank empties due to the reduction in weight, being stuck on the side of the road having other drivers laugh at the "hybrid that ran out of gas" is more than enough incentive to never push things too far (at least for me ;P).

Dave

 

<div class='quotetop'>QUOTE(CdnPrius06 @ Jul 6 2007, 09:00 AM) [snapback]473924[/snapback]</div>

I tried to "push it" this weekend and ran out of gas. I assumed that each bar represented 1/8th of a tank and thought that I had 60 miles left in the tank. Not so. After about 20 miles, it started to flash and then one minute later a red warning light came on. Very shortly thereafter, the car was out of gas. I ran for about a minute on the battery and then it was dead. Luckily I was able to coast down a hill to the exit ramp and found a gas station. What kind of idiot runs out of gas in a Prius? Me.

 

I fill up when the last bar starts blinking and I get the low fuel warning. Unless I know i'm gonna be in the proverbial middle-of-knowwhere at that time. And I'll fill up sooner.

 

<div class='quotetop'>QUOTE(john1701a @ Jul 6 2007, 06:15 AM) [snapback]473930[/snapback]</div>

I can't see anything wrong with wanting to know how far you can go on a tank of gas. What if you wanted to make a trip of 485 miles to a city with cheaper gas? Which is usually the case in this area. I can almost count the gas stations on one hand between here and Las Vegas, and guess what the gas price does in rural areas. With previous cars I knew the exact gas tank capacity and could estimate my range reasonably close. With a Prii and the bladder unfortunally it's not an exact science. Although I would hope to be able to make a trip of 500 miles without any problems; which for me puts Las Vegas and Los Angeles in one tank range bypassing all the high priced gas in between. Time will tell.

 

...So does the gas guage go from 2 solid pips being lit, to 1 solid pip, then eventually to 1 blinking pip? Or straight from 2 pips, right on to 1 blinking pip?
Out of curiousity, I'm interested in driving down to 1 blinking pip---but I haven't tried it yet! (Being that most of my driving is local northern-VA commuting inside the DC beltway, there's always a gas station somewhere nearby, so I'm not worried about actually running dry.)

 

<div class='quotetop'>QUOTE(ChristoB @ Jul 6 2007, 02:37 PM) [snapback]474155[/snapback]</div>

I goes from two solid pips to 1 solid pip. It doesn't take long to go from the solid pip to the blinking pip though, and once it starts blinking, its all over. From now on I will fill up as soon as it gets to two bars.

 

I usually fill up as soon as it gets to one bar. Note to original poster: Do a search on Priuschat for "guess gage" for interesting information along those lines.

 

<div class='quotetop'>QUOTE(jjv @ Jul 6 2007, 02:43 PM) [snapback]474159[/snapback]</div>

Yeah when its flashing you don't have long especially if you are in warm up stages. If I remember correctly I think I went about 15 total miles with mine flashing before I ran out. And now that I think about it, it was all on a cold start.

 

"I have gone 450 miles and I am down to two bars on the fuel gauge. I want to push the car as far as possible to see what mileage I can achieve, but I also do not want to run out of fuel."

It doesn't matter whether you drive 450 miles, or 45 miles when you refill. The mileage will be the same. Why is everyone so obsessed with squeezing every mile out of a particular fuel load? I don't get it. I fill up with 2 bars showing, and have only seen the blinky 1 bar once. Once was enough for me.