question on gas gauge

I usually fill up about 9 gallons, I've filled up only 3 times so far. First couple were just under 9 gallons, last one was 9.3 Its standard for there to be a couple gallons of fuel still in the tank even when it says empty, that's true for any car.

 

The Prius has a bladder inside its tank. The bladder, when stretched to its absolutely maximum capacity, can fit 11.XX gallons of gas in it. However, under most circumstances, the bladder does not stretch that far. Its ability to stretch is dependent on several factors, the weather (temperature) being one of them. Because of this, you don't really know that you had 3.XX gallons of gas left.

If your gauge is blinking, you definitely need to stop and gas up. Various posters have tested how long they can go on one blinking pip but there doesn't seem to be a set number of miles. If I remember correctly, I've read anything from 10 miles to 30 miles. Regardless, it's not worth risking running out of gas, in my opinion. I gas up at the latest when I get to one non-blinking pip and normally around two pips.

 

Not only that, because of the bladder you can't assume you had 3 gallons left, just that you could only put in 8.

Here's an experiment to try at home (tongue in cheek here). All you need is:

1. Bucket with level markings
2. Brick or large rock
3. Water

With your parent's help, carefully place the brick into the bucket. Next fill the bucket until the level is at the gallon mark. Did you really put in a gallon of water? Remove the brick (or rock) and see. Now, the gallon mark represents the level the gas gauge and the fuel pump says is full, while the brick represents the bladder. Some days that brick is 1.5 times as big and some times 3/4.

After the experiment, use the water to water your plants. They'll like that!

Yes, it was tongue in cheek, but it illustrates to me what the bladder does. If you want to visualize it, think of it like a balloon inside an old fashioned milk bottle. The balloon is stiff when the Prius is new and in cold weather.

 

Yes, what you describe is exactly normal for the Prius. It isn't desirable, but it is normal. It seems that our tank goes about 460 miles, give or take a few miles. We average 45 MPG, give or take a few 10's of a gallon. So, this means either, we can only get 9 plus gallons into the prius gas bladder, or that there is some problem preventing the Prius from using the remaining 3 gallons. We've actually run out before, when the car was new to us and we were expecting to get about 540 miles on a tank. We did not realize, at the time, that only around 9 gallons or so seems to be used. By the way, we have never had a fill up where we got in more than 9 gallons.

So, 45X9 gives us 400 or so. We refill when the trip meter shows somewhere in the 300's. We'll never push it further than that again, if we can possibly help it.

Personally, I think this is a real problem with the car, but it seems that the general consensus is that those of us who mutliply out what we expect to get on a tank, and plan to stop a gallon or so short of the expected empty point are asking for trouble. So maybe this is part of that Prius state of mind everyone talks of. I know I am sick of going to gas stations so often, but I guess if this is what it takes, it is a small inconvenience. I sure don't want to run out again. My other car goes way over 400 miles on a tank. It is a 98 Accord, with a 16 gallon tank, I believe, and 32 MPG on the highway. So in this one department, we have taken a step backward.

 

I have been averaging close to 500 miles per tankful of gas, which during our trip from Pa to Las Vegas meant stopping for gas once each day. Upon return from the trip, I noticed that I could not get as much gas in the tank as originally and the dealership explained that the bladder shrinks in the winter (owners manual says it will take 1.2 gallons less)

At this point, I am only able to get about 8.5 gallons in upon seeing the blinking indicator. So this means a full bladder 11.9 gallons will give you about 535 miles (avg 45mpg) where 8.5 gallons will only give you about 382 miles per tankful. This bothers me too but not enough to get rid of the car. I am anxious for summer so that I can see whether I can once again go 500 miles on one tankful of gas.

Don