not 600 miles?

1/4 tank would be 2.9 gallons?

 

So it has too much?

So it has not enough?

It seems that your two paragraphs contradict each other.

 

Oops! I meant 1/4 gallon!!

 

And some just cheap out on measuring accuracy, going with something sloppy and coarse, then set the reserve high enough so that the units on one end of the measurement error distribution aren't too low. At least, that is my only rational explanation for my car that had the highest "empty" range.

 

A quarter gallon would only get a Tundra 5 miles. Even in a Prius that might leave the fuel pump with inadequate cooling. Toyota likely set these low fuel light limits before they sold the Prius, and tailoring it to individual models is very low priority. they are calling for oil change intervals at the same distance and time regardless of whether the car is an ICE, hybrid, or PHEV.

Can't overlook what the displays would show with an high precision gauge and fuel sloshing around with the car in motion.

 

Geez, I remember my old F150 with the dual tanks, you knew you were getting low when you had to flip that switch. I couldn’t imagine filling up that bad boy with today’s gas prices. Definitely could cover some decent ground though with the dual tanks. I did drive it clear across the country fully loaded up and towing a trailer way back when I moved and flipped that switch plenty of times

 

the trouble with too much reserve is that i never venture into that territory, so if i have too, i get nervous as all get out. it's like ev range anxiety

 

There is considerable filtering applied to the gauge display already. A OBDII-port monitor (e.g. ScanGauge-II) can show the unfiltered sensor reading, and plenty of sloshing is visible, equivalent to multiple bars on my Prius gauge.

While I'd love that degree of precision and accuracy, it would suffer from the slope problem, giving different readings on level vs steep uphill vs downhill vs seriously tilted sideways while parked. A quart might not be enough to keep the intake covered in all those cases. Never mind the sloshing on hard corners.

And even without any tilt or sloshing, a quart won't be enough margin to prevent angry calls to Customer Service when unfavorable fuel consumption conditions causes fuel to deplete earlier that expected. Foul weather, mountain climbing, strong headwinds, and other factors could easily cause a trip segment to burn more than an extra gallon between available fuel stations. Quarter gallon resolution will draw some drivers to start such segments believing they have enough, when they don't. After they get stranded, eventually rescued, and return to cellular service coverage zones, some will likely burn the ears of some unfortunate call center rep. Designing in more safety margin will go a long way to reducing these angry calls.

 

Just occurred to me, how a “quart” got it’s name.

 

Sounded like being on a slight slope, combined with the tank shape and sensor location, is what was causing the fuel tank issues with the Rav4 a few years ago. Then Gerdes managed to get well over a gallon, maybe two, of gas over the official spec of a F150.

Car fuel tanks are shaped to fit into the available space. This does not lend them to being good containers for measuring volumes.

We likely started with imperial or standard systems of measure, because doubling or halving things is mentally easier for humans than working with tenths.

 

Today I drove exactly 600 miles on a tank of fuel ... 85% freeway driving. LA to Scottsdale then to Mexico. The rest was some in town driving around Scottsdale and Tucson. While in traffic I was (using Traffic Jam Assist) reading the owners manual and browsing this forum. Under 25 MPH the autopilot works well hands free. I thought I would intentionally run the car out of fuel and see what information I would be able to capture from that.

Low fuel light came on at 508 miles on this tank. Still showing I had about 23 miles of range on the ICE and I also had 77% state of charge on the battery. I kept driving at 100 Km/h to see how much further I would get. I had a 2018 Prime as well, and did the same experiment. And there are some differences.

At 533 miles on the tank I reached 0 miles of range, as seen in the photos. I kept driving ... and driving ... another 67 miles.

Finally at 599.3 miles to the tank I finally exhausted the fuel. Got the Christmas Tree dash going ... sorry for the blurry photo I was still driving.

Another 9 miles on battery to get to the gas station to fill up. Car took 11.55 gallons of fuel. Filled to the auto stop then one more squirt to auto stop again.

All the lights went out but the check engine light because the ECU threw a code. Anyways I will check it with Techstream in the morning and reset the code(s). What's interesting is that on the gen 4 Prime it was seamless to run out if fuel ... you could only tell by noticing the battery start depleating. If you weren't paying attention you could easily delegate the battery. On this gen 5 it throws codes and notified my phone was well. The other thing is that the battery range or percentage remaining was redacted after the ice ran out of fuel. So you can't tell how far you can go on case of emergency.

I don't recommend using the battery as a backup for extra range on a road trip. But in a pinch it can get you home or to the petrol station. Just remember there are two fuel pumps in this car, one low pressure and one high pressure and it's not good for them to be starved. My guess is that because of the additional high pressure fuel pump, this model doesn't seamlessly just switch to EV mode.

I manually divided 11.5 gallons over 600 miles to get about 53 mpgs. Some long climbs across the mountains coming out of Cali and all uphill from Scottsdale to Mexico.

PS I keep getting errors when I'm trying to upload the photos. I'll figure it out tomorrow and update the post.

 

It’s the site; uploads been broken for a couple of months now. Per the link about server migration at top of page.

 

So you still had about a gallon of gas when your distance to empty went to zero.
I did that to my old Prius C, but chickened out around 20 miles in when I ran into a gas station. I think the next gas station was another 20 miles out and didn't want to be stuck in between, since no EV only in a Prius C.

 

I normally wait until a low-fuel warning comes on before refilling. However, last night, with zero EV range left, 50 miles left on the DTE display, and a 57 mile trip home, I decided to finally fill-up my Prime for the first time. I got 8.5 gallons in it before the pump shut off. I was surprised, since I knew that the tank had a 10.6 gallon capacity. I thought I'd get closer to 9.5. I was immediately reminded of how my gen 2 wouldn't fill to full capacity in the winter due to the internal bladder not being expanding all the way, but I knew they got rid of that feature in gen 3. I figured then that the DTE and actual gas left don't quite line up, especially since I don't recall getting the low-fuel light.

 

On earlier generations, DTE=0 does not initially mean tank empty, but a safety margin remains. For Gen3 and 4, the Owners Manual gives an approximation, but many of us found a bit more, around 2 gallons. Though during a Gen5 discussion on some other thread here, I couldn't find a concrete number in this year's Owners Manual.

This safety margin is not universal among brands and models. My Subaru has no margin. Though it blanked out DTE below thirty miles, an extrapolation suggested that DTE=0 was very close to where my tank did run dry in a deliberate test. Instead of margin, it gives more stages of low fuel warnings, and makes them more visible, much harder to ignore or miss.

 

I had a friend with a VW like that. However, my understand was there were two tubers in the gas tank. The normal only reached down so far and when you switched over by rotating 180 degrees, the second tube went down further in the gas tank. No gas gauge at all.

My first high fuel car was a 1985 Honda CRX HF. I have have had 2010 , 2014 and now a 2023 Prius in addition to a 2011 CT200h. Four Toyota/Lexus hybrids now and one Manual shift performance car I kept for fun

 

Yeah my dad would check the gas, say if we were going on trip, with a stick.