Questions about gas tank and my MPG thus far

No bladder.

 

Maybe focus on mpg, rather than miles per tank? Fill when it’s getting lowish (on the gas gauge), and calc the mpg.

 

According to Toyota, the tank holds 11.3 US gallons. Thankfully, the light comes on before you run out of gas so you have enough gas to go get gas. When I was on a trip out west, I bypassed a gas station because I still had just over 1/4 tank left. The next station was so far away that I was close to 100 miles beyond zero on the remaining fuel gauge when I finally filled up. I was sweating bullets!! And it took 10.26 gallons to fill it. could have gone farther. I do NOT make a habit of seeing how far I can go on a tank out on the road.

 

On my Gen 3, I took a trip and the gas indicator came on. There is also a trip meter setting that estimates how far you have to go before empty. I was in the negative miles before I bought gas. I don't remember how many gallons it took though.

 

Yap, the light comes on before the tank is empty. It's a warning light. Anywhere between 1.5 to 2 gal of gas is left when the light first comes on.

 

Just went through this exercise of what size is the gas tank and why can't you fill with that amount on a Rav4 hybrid.

The tank size (allowed to be stated that way by the US Government in 2 government documents I've seen) includes three parts. The large usable amount. Below that in the tank a smaller reserve. And above the auto fuel shut off point a small splash area that prevents splash back into the evaporation control system (for which you will be responsible). The automatic pump shut off is supposed to be triggered at the point where you reach the top of the usable area and the bottom boundary of the splash area.

Some systems have a warning to get gas before the needle is at empty, then an empty light and only then you are into the reserve.

You never want to run the tank dry. Sediment collects at the bottom and on some cars the fuel is used to cool a gas pump inserted into the tank.

Bottom line: don't be expecting to fill with the amount of advertised fuel tank capacity

 

Talk about 1st world problems.

At 68 years old (in a few days anyway) my 2005 Prius was the first car I'd ever owned that had a DTE indication or a fuel light. Just a very non-linear needle gauge. That was insane and it was how we drove for almost a century.

 

I would hope that drivers understand that it is desirable for the low fuel light to come on before the tank is actually empty. Yes, they have some built in safety margin. For the Gen3, it was about 2 gallons, see Bob Wilson's testing results:
[WARNING] Running out of gas (Gen III) | PriusChat
Here is his Prime test:
[WARNING] Running out of gas | PriusChat

Compared to my past cars, that is normal. But you must still be mindful of the gauge before the warnings ever appear, because we have lots of places like these, at least on my side of the continent:

 

On the Gen3, that meter does not display negative miles. It stops counting down at zero.

 

For RTFM fans, here is what the 2021 Prius Prime Owner's Manual says, on page 676:

The Rav4 Hybrid has a particular problem, and Toyota offers a fix for it:
Toyota RAV4 Hybrid Fuel Tank Issue Fixed By Customer Support Program | Torque News

On a Gen3 or later Prius, if one really wants to use nearly the full fuel tank capacity, one can, and numerous folks here have done so. Just be well aware of the risks of miscalculating or mis-forecasting and getting stranded when you get it wrong.

BobW intentionally ran his Prii out of fuel more than 50 times, for a variety of fuel and engineering tests, and reported a lot of interesting finds back to the readers here. And he never suffered any adverse consequences of the sorts offered by the various scaremongers.

 

It's been a while. My wife was panicking. For some reason, I wasn't.

 

My Subaru has a different low fuel warning scheme. Its DTE has no safety reserve, it aims for 0 miles to be at the same point the tank runs dry (though the number is blanked out some distance before that). But it has multiple other warning at earlier stages, a couple of them in contrasting in-your-face colors (much better than my Prius), so there is no excuse for missing them and getting caught unawares.

When I was away, my spouse was driving it for a hiking day with a friend. But she confused the Prius vs Subaru rules I had tried to teach her. She thought that despite all those other warnings, she could continue past DTE=0 and make it home without stopping to refuel. The friend was getting nervous, and then finally panicked and made her get gas.

Good thing, because it wouldn't have reached home. Having myself intentionally run it out of fuel previously as a test, I'm surprised it didn't run out on her. The numbers on her partial refill, and my subsequent full refill, suggested that she got almost 0.1 more gallon out of it than I did. And I ran out on a flat road segment, she still had a 400 foot hill climb ahead of her.

 

Compared to what?

My first Subaru had nearly 1/3rd of its fuel range below the E mark, though that was the exception in that direction. In the other direction, an earlier car stalled from fuel starvation with its fuel needle still above E.

Otherwise, about 100 miles past E or the low fuel light has been about average for my cars.

 

Put 1-1/2 gallons in a container shaped like this and it won't be very deep.