Questions about fuel gauge from a new prius owner

I've owned my Prius about 8 days now, when I bought it it was on the last pip on the gauge (maybe two pips left not really sure) so I immediatly filled it the tank took $25CDN to fill (about 22L of fuel), I think to myself wow small tank. I get the car home and start to read the manual and find out wow the tank is suppoosed to hold 45L of fuel. Now I'm confused, but maybe the gauge was higher than I thought. (confused). So I drive the car all week watching the fuel milage and gauge like a hawk. This morning on my way to work 140km round trip each day the gauge drops to the last pip again (10km before I reach work). The computer says I've averaged 4.6L per 100km (62.77mpg) not bad. with a total milage on this tank of 600km. (math side of this) 600km @ 4.6L per 100, 6X4.6=27.6L. So the gas I've burned is approx what I thought I put in the tank.

Now this will all be approximates but here goes, I understand that the gauge in the prius is not known for it accuracy and that Toyota has made a few liters of fuel non useable for cooling and such, so if the tank holds according to book 45L, 5L of it being not useable(approx) that leaves 40L of useable fuel, now if the bladder type tank varies the amount of fuel you can put in a fill up due to temperature and I have used 27.6L of the tank, that should leave me between 10 and 13L of unused fuel still in the tank that my gauge isn't showing. This leaves a few possibilities,

1- my gauge is way out of cal.
2- I have the smallest tank installed in any prius on the planet (I doubt this one) or
3- the previous owner used the car to smuggle crack and once I open the tank I'll be rich.

I do not want to run the car out of gas but, I really need to figure this one out. If I understand the system correctly the last pip will begin to flash once I reach the as per say reserve fuel, giving me approx 50km till I'm really out of gas (last pip not flashing yet), so should I push the tank and see if I can get another 300km (approx) out of it telling me the gauge is really out of cal or not, or if I run it out of gas before that than I'll fill it to see how much it holds.

(side note) 600Km on a tank seems very low compared to numbersI'm seeing by other members on this site, but I have no personal experience.

Any comments/suggestions would and will be of great appreciation.

 

I don't think its a way to fill the tank thing as that might explain few litters but I can't beleive it would affect around half the capacity of the tank but I will look into how to fill your genII gas tank.

Temp in Ottawa when I filled was around 50'F temp today 35'F, so your telling me there is a 4 gallon difference in Mississippi between summer and winter???

Because if thats the case I would be very interested in what the temperature shift is for you as here in Ottawa summer temps are around 80'F winter tems are around -30F making it about a 110'F temp swing so in the winter I should get around 2 gallons in it.

 

I think I understand a little better how the system and blader work. I will fill up at 2 pips makes sense to me. I did try and push it on my way home that night and I didn't make it home without gassing up, but I know that the blinking pip and the audible chime when the blinking starts all work. once the blinking started I found the closest gas station I could find off highway 416, in turned out at that time to be about 18 km after the blinking started, I was a little worried I won't make it but I did. It took 27L of fuel to fill again, temperature was around 10'C (52'F) I never was one of those that wanted to see how far I could go on a tank of gas I just like to have an idea in case I'm ever in a situation that I have to push the car, I like to know how far I can push it, if and only if I have no other choice.

Thank you eveyone for your input it was appreciated and needed.