Ran out of gas: what happened (or my first 500 mile tank)

I am comfortable going a little beyond start of flashing pip in the 2010 (north american gen2 bladder tanks, stop at 2 pips), and believe there are maybe 2 gallons left at the pip flash.

But I gain NOTHING if my wife runs out of gas...

...so I fill up around the time last pip flashes, if not before.

 

I think there is enough info going around in these threads for some time now that I'm going to drastically modify my original intentions. Right now I'm using up so little gas that I'm impatiently waiting for each bar (pip) to drop off on the gauge. Assuming I am driving around locally and not on a long trip I'm just going to varify the rough linearity of the gauge as gas is used up down to the last bar starting to flash and then fill up the tank full noting the gallons added. From what I've been reading I should be able to glean a pretty good idea of how much gas was left and not be concerned about how many more miles I could drive before running dry. Because normally I don't press my luck past empty. I'm going to fill up depending what stretch of driving I'm doing when the tank is around 1/4 full.

All bets are off if when the last bar starts flashing I add 11.9 gallons to the tank.

 

Bob,... You say the can fits into the left compartment hole next to the 5th door. That's a great spot but is it low profile enough that you can put the cover down on top too? Do you always keep an extra gallon in the car or _only_ when you are fiddling with the fuel gauge?

I apologize--I'm going to post this anyway before looking again to see if you clarified how you calculate putting 12.1 gallons into an 11.9 gallon tank--or do you consider, as I might, that 0.2 gallons error is a resonable tolerance all things considered?

 

Got a little carried away a few weeks ago. I left the house with 2 pips but a few miles later it was showing 3 pips - so I knew I had a few gallons in there.

20 miles later the MPG gauge showed 99.9
20 miles after that is was still over 95 MPG

I soon forgot about filling up and decided to see how far I could make it on a single gallon. (I had reset the trip odometer before leaving). The odometer - going up - and the MPG's - going down - finally crossed each other at 89. 89 miles on one gallon of gas! (And an average speed of 54 MPH).

After that thrill - I quickly headed for a gas station!

 

The spout is above the floor level so the carpet covers it but the end is visible.

I only carry the extra gallon when doing mileage or tank tests. Otherwise, I prefer a flat, rear floor. I think a small, one gallon spare can could be designed that would fit in the space, flush. With provisions to handle a 'fume space' for thermal expansion, it would be a great product.

I suspect the traction battery provided extra distance that might have distorted the gas used after the initial "flash." Because I don't have a "check engine" light that lets me know when the last of the gas is gone, it could lead to extra distance and distort the amount of fuel calculated under "flash." Then there is always the hypothesis that tanks may not be uniform for all vehicles.

Based upon the measurements of our specific vehicle, 12.1 gallons seems to be reproducible. However, the difference between 11.9 vs 12.1, we're talking pretty small quantities. For my purposes, I have to know what my particular vehicle does and respect that others may get a different value.

Bob Wilson

 

For some reason I come really close to danger constantly...I think it is the lack of a low fuel light or the mile to empty display not being always on that is causing me to get within 1-2 gallons of empty. I am living dangerously.

Also if I reply to this post I get closer to pushing the Pugsy thread off the first page.

 

My first tank refill questions moved to own thread:
http://priuschat.com/forums/gen-iii...age-quantity-gauge-questions.html#post1083559