Ran out of gas with 9.5 gals out !?!?

As a newbie myself, whenever I see two pips on the gas gauge...it is time to get fuel. It is not worth to find out what damage this will cost me....c'mon....it is just going to be just a tad over $20 dollars to fill. For a new car and understanding that the fuel tank is a bladder type, I've never put in over 8 gallons of gas after 3K miles of driving.

 

I think this is an excellent point. A lot of people say not to trust the gas gauge. I interpret the situation exactly the opposite way. Trust nothing except the gas gauge.

I've never heard of a case like this, sounds like an anomaly (stuck float maybe?). The most common thing I've seen is the top pip can be larger than average, the ones in the middle can be a less than average. This really isn't any different than any other car. Many cars will peg the gauge at full for quite a while, then start to fall, move more quickly through the mid-scale region, and then slow down on approaching empty. There will also frequently be a fair amount of car to car variation on distance from when the light comes on to when you run out of gas. I also am really puzzled why people feel the need to second guess the gauge. Its doing some pretty complicated calculations near the top and middle of the tank since the size of the tank is constantly changing. Similarly, since the size of the tank changes, the effective volume represented by each pip changes. This can easily cause it to have to make corrections over time. Where it should in theory have the easiest time figuring out how much gas it has is when its getting low. When it says "add fuel", its probably not fooling around. You might get lucky and get 100 miles out of it, but whats the point? More likely you will end up on the side of the road, or end up stressing your HV battery getting to a gas station.

There are certainly times when you need to have a rough idea how far you will make it on a tank. In this case, it seems to me the only relevant number is how much you physically put in the tank on the current fill up. If it was flashing and you could only get 7 gallons in, don't count on being able to get more than 7 gallons out. There aren't many places in this country at least where you need to be able to guarantee that you will get 400 miles out of a tank. Its cool that you often can, but its really not of that much practical value.

Rob

 

your prior cars had a fixed volume gas tank.

the prius gas tank is variable size ; it changes ;it moves, it is alive and very fickle.

it has a different capacity every time you fill up ; depending on temperature , the flow rate/pressure of the fueling system ; and probably the age of the bladder.

its capacity is not 11.9 gallons.
it is a absolute maximum of 11.9 ; but on any given day it is almost certainly less.

this requires a mind set adjustment - we're used to fixed capacity systems from other vehicles, but the prius system is different - we need to believe the computer: when you get the flashing light, fill up, pronto.

 

So it was all about saving what, maybe 10c a gallon or 90 cents. I find each car I drive I need to get to know it before pshing the limits.