filling up gas

Having just one bar (pip) is not the warning for being low on fuel for a Prius. Having your last pip blink is.
When the low fuel warning starts, there is approximately 50 miles or so worth of gas left . . . sometimes more, sometimes less.

What causes some Prius drivers to push the limit and run out of gas is just human nature. But then, so is the act of overly cautiously refilling the tank long before it is necessary. By doing so, not only are you needlessly visiting the gas station twice as often, you are on average carrying around twice the weight of gasoline . . . Neither of which are good for fuel economy for a Prius.

 

I will again comment that running out of gas in a Prius is an incomprehensible act. It doesn't take much time or money to fill the tank, and the full tank will last for quite a few miles. If you carelessly run out of fuel, you can badly damage your expensive car. It just makes no sense....

 

Does that small amount of gas really make a difference? In real world driving conditions that is? I haven't noticed reduced fuel economy on a full tank versus half a tank or less. Temperature, road conditions, inclines (or lack thereof), speed, stop-n-go traffic, tire pressure, etc all have a much more immediate effect on my mileage than a topped off tank.

 

Will anyone notice a MPG or two difference due to always having a half tank of essentially dead weigh? NO.

But for sake of argument, a half tank of gas (5.5 gallons) X 6.1 pounds per gallon = 33.5 pounds. Over the lifetime mileage of the Prius, yes, it will cost you money to drag that stuff around.

Another aspect to consider is the additional low MPG warm-up periods the Prius needs to go through due to turning the Prius off and on twice as often because someone is adding half a tank of fuel per gas station visit.

 

It's not human error, it's the mileage nuts trying to get the last bit out of the car. They are bound to run out sooner or later. I usually fill up as the gauge drops below 1/2, unless I'm on a long trip, where I fill up at customary stations. At the very worst, I've only gotten down to two pips, due to fuel stations being closed on a back road.

At least most of them don't blame the car. The ones who post it is a design fault are the ones who crack me up!!

If you run on or near "empty" a lot, sooner or later you WILL run out!

BTW, I doubt very much that it will do any harm to the car. You don't "weaken" the battery by stretching the discharge cycle in a NiMH battery. You either take one (or more) cells to 0 or you don't. If you do you damage those cells and thus the battery, and notice it right away (within a week). If you don't there are no consequences.
Unlike a lead-acid battery.

 

I always fill my tank at half empty which was a habit I picked up decades ago when I had a part time college job chauffeuring US Supreme Court Justices. Couldn't run out of gas with one of them in the car!

I still do it with our 2007 Prius. I may be carrying around extra weight, but I can still get 60 mpg on my runs to New York City from suburban New Jersey and that's good enough for me.

I also note that I never had the problem of the gas spitting back up at me at the pump, though I don't know if there is any connection.

 

Roughly 0.5 - 1 mpg over the lifetime of the vehicle (let's say 1 mpg), over 200,000 miles @ 50 mpg = 4000 gallons of gas vs 3922 gallons. 78 gallons * $4 gallon = $312.

And how many of us could stand to lose 30 lbs? A friend of mine who used to race bicycles in college was always amazed at some cyclists who would spend a few extra thousand dollars to get their bike down another 3 -4 lbs from the stock set up, yet were carrying an extra 30 lbs around their waistline.

You are assuming that one makes a special trip to the gas station (leave house, go to gas station, go home) for this rather than incorporates a trip to the gas station in their commute (leave house, run errands, go to gas station, go home).

Sorry, not really trying to nit pick here, (ok, a little), but just showing you that there are some assumptions and other items that while "technically" are correct, aren't that big an issue.