Ran out of petrol……

i'm glad you made it to the petrol station, .7 miles is very good at that speed.

i think your presumptions are correct regarding dte and low fuel light. i can't make any disparaging remarks because i've been there

 

Yeah, best not to drive it until its empty. If you need to, you should do the calculations yourself to determine how much further you can go.

On some recent road trips the gas light comes on with about 2-3 gallons left in the tank for me.

 

Thanks! I always wanted to know what happened when you ran out of gas in a Prius! Also, dang I need to upgrade to a Gen4 to get 57 MPG!

 

You have a 2010. Here is the best PriusChat write-up for your vintage, from someone who intentionally runs his vehicles out of fuel for various engineering tests and curiosity reasons:

[WARNING] Running out of gas (Gen III)

Here is his write-up for his 2017 Prime:

[WARNING] Running out of gas

 

My vintage heh
Neat, it basically turns into stealth mode

 

The 2020 Toyota Prius has a gas tank size between 10.6 gallons and 11.4 gallons depending on the trim level and model options. I'm guessing your year and model has the 10.6 gallon tank? Did you recall how many gallons you put in upon refill? And Do you know if to fuel pump stayed off upon driving it in limp mode

 

I really appreciate that you're giving us a look at how it all works when in that situation. I'm averaging about 39 MPG, so I wonder if that DTE calculates that?

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I've wondered if a hidden 11 ounce or 20 ounce MSR bottle of fuel would be enough to get the car going again if in the same situation, but then the question is - where to put that bottle? I don't want it inside the cabin.

 

I am sure the 10.6 gal tanks are for Pris AWDe models only. All other trims of regular Prius have 11.4 gal tanks (or 11.3 gal tank depending on which spec you are looking).

I think you are correct that the DTE miles remaining are dynamically adjusted most likely based on the way you have been driving in the recent past and actual gas remaining in the tank. So, 100 miles remaining displayed on the DTE may not be the same amount of gas left in the tank each time you see it. However, as you stated, the gas empty light always comes on at a very similar point in that it comes on when it reaches the last pip regardless of what the DTE displays. As stated in the manual, the PP which I think is similar to Gen4, at the time the gas empty light comes on, there is ~1.7 us gal of gas still left in the tank. With 54 mpg, you can certainly drive close to 91 miles after the empty gas light comes on. On my PP with no traction battery EV range left, I have driven over 100 us miles after the gas empty light came on without any problem. When I reached a gas station to fill up, the car took only 10.3 gals. Thus still ~1 ga of gas was in the tank.

 

I'd suspect that would depend on the slope orientation of the car. If it is tilted on the shoulder of the road, it may or may not be enough to reach the pump inlet.

On older generations, some drivers tried restarting too many times before adding fuel, setting an internal 'no fuel' flag that prevented additional restart attempts even after fuel was added. The first few to write here, had it towed to a shop to be reset, before others found that merely disconnecting the 12V battery long enough to clear memory, was sufficient to reset it. But others didn't run into this problem, including BobW who intentionally ran dry for various engineering tests. But since he knew he was going to run out of fuel, he probably didn't try any restarts before adding more.

On my older generation 2012, while climbing hills, DTE drops faster than actual miles driven (not surprising, as climbing burns extra fuel), and will suddenly and unexpectedly snap to '0', instantly losing as much as 12 miles (that I've witnessed, more may be possible).

Another part of the internal dynamic formula is that it must always decrement 1 mile for every 2 (or less) miles driven, even when gliding on long downhills burning no fuel at all. And unlike my Subaru, the Prius DTE can never ever increase except when adding a certain amount of fuel, 1 gallon isn't enough. I haven't figured out any more portions of its formula, and suspect that your newer generation would have only added more rules, not removed any older rules.

That is still my presumption, and I don't recall seeing evidence to the contrary. But do note that the fixed threshold may vary depending on slope, tilting the tank.

 

FWIW, I've read here that if you run it dry you need to add at least3 US gallons before the car will start the engine, presumably due something in the car's programming.

 

Is there a fuel pump safety that shuts the pump off?

 

I try n use 11 gas of gas every tankful.