How to run out of gas

I can answer only for my Gen3 Prius and 2014 Forester, not your Prime. In this situation, both of mine will see DTE decline faster than the odometer increases. I'd expect the same of your Prime.

In my Prius, no real problem as it has 100-ish miles of safety margin after DTE reaches Zero. See BobW's Gen3 out-of-gas thread, someone should do the same tests with the Prime.

In my Forester, on one hand, it is a big problem because DTE=0 (which must be extrapolated, because it blanks out at 30) really does mean 'out of fuel', so it will sputter and die before the end of your hypothetical 90 mile trip. On the other hand, it has four low fuel warnings before starvation occurs, three of them much more in-your-face and blatantly obvious than the Prius, so any reasonable human being cannot have any credibility claiming 'I wasn't warned!'.

 

I was 18, and that was the first tank of the first car I actually owned (though selected by parents and handed over to me). I didn't start tracking such things until six years later, after buying a car of my own choice, with much better fuel economy and range.

That experience was also not long after another learning experience, on a significant high school date. Parents initially refused me use of the good car, so I had cleaned / prepped / fueled the usual school junker ahead of time. At the very last minute as I was stepping out, they swapped cars on me, assigning me the nice but completely unprepped car (very dirty environment on dusty gravel and dirt roads). I asked dad if it had gas, he assured me it had plenty. But while picking up my date, I discovered the needle below 'E', so very inconveniently had to add a bit extra on the way to the venue.

Afterwards, both parents teased me about fearing driving with the needle only slightly below 'E', because they saw no risk. Mom continued rubbing it in while driving it deeper below 'E' for more than a week.

Lesson learned: When dad answers a question, his reply is often based on what he thinks I want to hear, without any connection to reality. Decades later, the more disabled and dependent he gets, the more often this happens.

 

On the other hand, running out of fuel in an airplane is a bit more awkward than in a car. My son is a commercial pilot, and he says that on small planes anyway, you never believe the fuel gauge. There is a dip stick into the fuel tank, and THAT is what you believe during the preflight check to verify that you have enough fuel.

 

That's how my dad checked the gas on our '58 VW. There was no gas gauge, wasn't a dipstick either: he just kept a stick under the hood. Where the gas tank was, engine 'round the back.

 

Had a friend in high school with the typical old car that a teenager often drives, don't remember what kind it was but the fuel gauge had gone out, and whenever he had his sun visor down you could seen where he had been writing the odometer readings onto the visor each time he filled up, and he used that to calculate when his next fill up would be needed. Teenagers of course are experts at knowing exactly how far they can go before they run out of gas, probably better at it than even Bob Wilson!

The visor had dozens of entries, and if I remember right the visor was about 2/3 full. What he did when he eventually ran of space on the visor I don't know, maybe start writing on the front of the visor, or start writing on the passenger visor, or get a new visor (unlikely), or get the fuel gauge fixed (highly unlikely), or just get another car (most likely)

Okay so why didn't he just write the odometer readings in a notebook? Remember, teenager.

 

Well I still haven't brought the "fuel low" lamp on. I had (for my old Civic Hybrid) only enough gas to do an 80-mile trip maybe 1.5 times, and I had two of them to do. But with the Prime now, I charged up at night before each one (shaving 25 or so freeway miles off of each) and after both trips, still had plenty of gas left -- enough where the fuel light still didn't even come on. But I was driving past the cheap gas station, so I filled it up -- the first time I've ever filled up the car since getting it (1750 miles ago). Other than today, I only once put in $10. And most of my trips are well above the EV-only range. So I'm impressed, to say the least. Even in HV I'm getting mid-to-high 60s in MPG.

Except now I have a full tank of gas (extra weight to carry around). In my old car, I'd be the type to fill up anytime it was under 1/2 full if I was passing the cheap station. Now I think I'll wait until it's under 1/4th full, since the range on this car is so much greater and all that gas is just extra weight having to carry around. But I wanted to be able to say that I "filled it up" at least once

 

Sounds like you are driving an '81 Bonneville, what are you doing paying attention to gas prices? Time to break that old habit. For the little that you use, and especially since the gas will be sitting in your tank for a long time you should be concentrating on the quality of gas that you are putting in. Easiest way to do that is to use one of the majors (yes I realize it will be tough at first) or if you still want to think about prices then at least go to one of the lower priced Top Tier certified stations like Costco (if you are a member) or in your case in California maybe ARCO. A list of Top Tier brands is available at Licensed Brands | Top Tier Gas

 

Actually, the cheap station's gas is quite good, and no different than the other stations. There are actually only something like 5 refineries that make the special gas Calif requires, so at least in Calif, there's very little difference between the brands (other than marketing and additives), since they all come from the same (I believe it's 5) refineries.

 

It's all about the additives, that's the difference. Additives are added to the fuel after the tank truck fills up at the distribution center. I have heard that sometimes its added after the fuel is pumped into the storage tank at the gas station. This is where discount gas retailers can cut corners by using inferior generic additives. The EPA set some standards several years ago which helped, but they were too low and automakers were getting concerned. BMW, GM, Honda, and Toyota got together, and based on their own research as well as input from other car makers worldwide, set a higher standard which is now known as "Top Tier". The Top Tier standard concentrates mainly on the gasoline's ability to inhibit engine deposits, but also specifies that the fuel must be free of metallic additives.

Gas retailers can voluntarily submit to the higher standard and receive Top Tier certification. Or they can choose not to, which allows them to undercut the competition by a few cents, knowing that many people will choose one station over another for even a one cent difference in price. As I mentioned there are some discount brands that meet Top Tier standards, it's worth going to one of those even if the station across the street is a few cents cheaper.

 

When I highlight gas price differences along my trip routes -- even 60 cents/gal in a single block, 100 cents/gal within 2 miles near my home -- I am including only Top Tier sellers, not any substandard discounters.

 

Well, I finally filled up a 2nd time and my car too over reports the gas mileage, but only by 4.377%, but that too is probably close enough to yours that mine will probably end up close. Sill, not bad, I got 85.28 MPG, which is higher than I calculated by Toyota's MPG numbers by a couple of MPG. (My commute is about 70 miles and I can only charge at home) I love being able to go over 800 miles on a tank!