Testing the limits of the fuel gauge

Someone else has already done it for us. Try reading just the first post of this too-long thread:
[WARNING] Running out of gas (Gen III) | PriusChat

 

I never look at the DTE figure. When the last pip goes flashing I reset trip B and know that I have about 9 liters (2.37 gallon) or some 200 km (120 miles) left when I drive normally.
I regularly fill up 43-44 liters of the 45 litre tank (11.3-11.6 gallon).

 

I do the same. I reset trip A when I hear the low fuel beep. I know I can easily drive another 70 miles before going to the gas stations.

 

His method is great. But the limits to which he pushes his refills should be reserved to densely populated (and serviced) flatland regions. Drivers living in sparsely populated mountainous regions should be doing most of their refueling significantly earlier.

 

Don' understand, this pursuit of emptiness... I've got a just cracked kilo of coffee beans in the cupboard. And an unopened bag ready to go, on the shelf in the garage. Wouldn't want to run out.

 

I lived on the edge so to speak for quite some time, but when it came to the gas gage I learned a LONG time ago not to play that game. It is a sinking feeling when you lose power especially if you are on the super slab and by your self. I did that one time when I was 16 years old. Driving a old Ford Pinto (explosive gas tank!) and knew I needed gas. I was following someone else. Needless to say I ended up running out of gas and had to leave the car overnight on the side of the road in Kentucky of all places.

I was really surprised to see the Pinto sitting there the next day and not up on blocks or worse not there at all. From that one experience I have never allowed any vehicle I drive to get below 1/4 tank. And if I did push on to 1/8 that was the absolute limit. If I am in unfamiliar territory I have been known to start looking when I hit 4 pips unless my Garmin shows a Shell ahead of me that I can verify is open by making a phone call.

Only one time have I pushed the current Gen III Prius down to the flashing pip and that was just to see if I could get 500 miles on the tank.

Call me chicken if you want, I just don't like walking and being stranded. It always seems to happen in the worst place possible.

 

For me, a PIP typically signifies 50 miles of gas (on average). Flashing starts at 25 to empty.

Not a perfect science, but it's worked so far. I've gone past the DTE figure many times without a problem, though. If my DTE is under 45 before I head home, I get gas first.

 

Some things are actually very important, so do keep a good stock of those caffeinated beverage products. The spouse is a tea drinker. It is easy to see there is a real physical addiction. I get reminded every time the schedule is interrupted by external factors, and the withdrawal symptoms start up.

My different cars have had vastly different mapping between the fuel gauge and the actual tank. Having a realistic feel for each car is very important if or when it comes time to choose among available options: go for it, vs. paying for overpriced fuel (gouging), or camping overnight waiting for closed stations to open, or detouring from the desired route to available fuel. If one has never tested the lower levels of a tank, then one is making decisions based on guesses.

Some people live in regions with little or no fuel price competition or diversity or gouging. That makes the tradeoffs much simpler.

That is why I intentionally test it early, in familiar places under good conditions when schedule doesn't matter. It is much better to discover adverse findings in benign conditions when they won't snowball into serious consequences.

 

Don't ever trust the blinking light. In my Volvo 960 I always thought that I could go 40 miles when the low fuel light came on or at least that was what I thought. I was out on I-77 the light came on and I thought no problem I'll drive for another half hour and get gas at a particular exit.
Twenty miles later the car ran out of gas. From now on I always fill immediately as soon as the light comes on or at a set mileage (500 miles) even if the light hasn't come on. Since that one time I ran out of gas I always when traveling long distance have at least a full five gallon Eagle Safety can in the trunk just in case.

The blinking PIP might work great at 1,000 miles but once you get five, seven, or even ten years on the car, things that normally work don't always operate as well as they did when the car was new.

 

Yeah but it's been tested time and time again by those who (bwilson4web) dare to try it that when the last pip starts blinking, the Prius can do at least another 100 miles before running out of gas. Nobody ever go that far before filling up. I usually drive 50-80 miles on flashing pip before refueling. The fuel gauge measures from 11.4 gallons to .7 gallons according to scangauge. This is why when you fill up your Prius, you can do almost 100 miles before the first pip disappears and why you can drive another 100 miles on the last blinking pip before running out of gas. I don't know about other cars but on a gen 3 Prius, when the last pip starts to blink, you have about 2 gallons of gas left. This is why so many people complaint about only able to put 9.5-10 gallons of gas when they go fill up their tanks right when the last pip is flashing.

 

after hearing the beep and seeing the blinking pip in my '08, and resolving to fill up at the next opportunity, i proceeded to completely forget, and ran out of gas on the way home from work. had to walk 2 miles home in a cold rain and get triple a to come add a few gallons.

i know head for the gas station when the pip blinks.

 

08 has collapsible tank so you dont get a constant left over fuel for every single low fuel situation. Gen 3 on the other hand has regular fuel tank so each time the low fuel flash, you have about the same amount of fuel left as all the other times. Now, I'm not saying you should drive 100+ miles on the low fuel flash but it is safe to say that you can drive another 40-50 miles before you absolutely have to go get gas. Even then, you still have about 3/4 to 1 gallon of gas left. When you do go put gas, you still won't come close to put in the 11.9 gallons of gas unless you over fill your tank.

 

Regardless of how much farther we "can" drive after the low fuel warning or after the last pip, isn't it best for the fuel system to not always suck the tank down to the last little bit where it's more likely to get into any crud in the tank as well as causing the fuel pump to run hotter (not being submerged in a nice big cool gasoline bath)

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I never really believed that argument because the fuel pickup is always at the bottom of the tank, where crud will also accumulate. After a night standing then I would argue that all the crud has already sunk to the bottom and will be the first to be sucked in to the fuel filter.

 

What about the cooling effect of being submerged in more gasoline?

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What about running out of gas? Or inconvenient, extra runs just to get gas? Or, if you're trying to track tank mpg, the ultimate spanner in the works: someone else tanking up? Or putting in "10 bucks worth"?

You can recover from the latter, well if you've got the gas receipt: just lump it in with the next tank. But anyway, if you're thing is running down to fumes, good on you, but keep your AAA Membership up to date, lol.