The Prius gas guage

Owners of the previous prius generation kept getting stranded because they won't fill it up when it was much accurate, I mean they said the head space was too slim. To minimize that, the turd generation was built with larger headspace, point fingers at 2nd generation owners

 

toyota believes in large safety margins.

 

It is a safety margin, or reserve, to reduce the number of people who get stranded by fuel starvation.

I've never had one of those cars with a warning at just 50 miles. All (but one) of my pre-Prius cars had at least 100 miles of reserve. (The single exception had negative margin -- it ran dry with the fuel needle still above E.)

Since getting my first Prius, I now have a Subaru that gives its first (of 3) warnings at about 75 miles.

Safety margin is necessary because fuel gauging isn't perfect on level ground, gets worse when the car is tilted (front-back and side-to-side), and fuel consumption is far move variable than most people realize (weather, temperature, water-snow-slush on road, wind, mountain climbing, external racks, cold starts, short trips, etc.). Most people are not good at accurately mentally figuring fuel consumption in those degraded conditions.

If the fuel gauge was truly "accurate" on average, then a lot of people cutting close to the limits would be caught by the unplanned negative swings of those variables. Then the Customer Support call centers would get hit with many angry owners claiming -- correctly even -- that "the Distance To Empty gauge said it had enough gas to get there, but it ran out early, stranding me in a remote place in the mountains without mobile phone coverage on a dark and stormy night!"

Some people will run dry regardless. Toyota puts in enough margin that no one can legitimately claim insufficient warning.

Think of it as "customer expectation management". There are many other elements of this built in to most cars, to make owners feel better and reduce complaints.

Where I occasionally drive, 50 miles warning is simply inadequate:

 

Note where the gauge is, and how many gallons it takes to fill. Then you know the correlation.

 

Are you trying to tell us that you get OVER 60 MPG with your car ? Doubtful.

ALL cars show "empty" before they really are........to try and help keep people from doing stupid things.
Obsessing over exactly how each model accomplishes that is........obsessive.

AND.....making one or two "extra" stops for gas during your trip is.....NOTHING.....in the overall scheme of things. Driving more than 500 miles straight without stopping is NOT a good idea, even if your bladder will allow that.

 

That safety margin won't go very far in that condition either, and depending upon it carries added risk. So "acting accordingly" is not a wrong choice in circumstances where running out of fuel causes a significant problem.

Here is the best Gen3 fuel tank capacity test thread, though you can get everything you need from just the base post and skip the 487 replies:
[WARNING] Running out of gas (Gen III) | PriusChat

... or the vehicle specifications list in the new car brochure, or the Monroney sticker (required window sticker on new cars), or Fuel Economy, or ...

It become quite obvious when one compares the listed tank capacity to the gallons pumped during refills.

This isn't about not making bladder stops, this is about detouring or changing routes or plans in order to get to available fuel before running out.

 

You are assuming that.
That is not exactly what he said.

I do find it rather odd that he seems not to have figured out how it works before his long road trip.
Unless he just acquired the car and immediately hooked it up to something WAY over the engineered towing capacity and just took off on a long trip. The result could have been much worse..

But the whole story really doesn't make any sense if you think it through.
It seems he is saying that he actually DID plan his stops a bit sooner than would have been necessary......if he had known the tank was bigger. That is NOT a problem. Just a minor annoyance.......maybe.

 

RULE OF THUMB: In average highway conditions/driving, when the DTE hits ZERO miles to go, you can always go 50 miles more.

There was a thread on this a couple of years ago.

SECOND RULE OF THUMB: A thread about the fuel gauge "bars" or "DTE" gauge brings out the worst in people. Your actual question will be ignored and they will tell you how stupid you are for driving after X bars or when there are Y miles left on the DTE. Or they will flame you for driving Z miles without stopping, or say you are silly for not wanting to stop for gas more. Not sure why people get their knickers in a twist on this subject, but it happens every time.

 

Drivers towing 1400 lb campers should adjust this rule downward in proportion to their towing vs non-towing MPG.

 

I don't think by Toyota

 

Right -- the 50 miles after zero DTE is only under average conditions -- towing is definitely not average in a Prius!!

Right. The OP is confusing Gen 3 with Gen 4. The owner's manual for Gen 3 specifically says no tow capacity not even a little. Gen 4 has a maximum towing capacity of 1,598 pounds. When publicizing the change, Toyota noted "heat management measures that have been introduced in the hybrid system's main electric motor-generator and the differential" permitted the new towing capability.

 

Yeah even 4th, North American at least, excerpt from 2016 Owner's Manual:


Basically, not even a trailer hitch just for bike rack, etcetera. That's a little draconian, but...

Maybe you're thinking of European Toyota stance? Seems to me some places they condone towing for 4th gen.

 

Yeah, there have been some articles on that and the politics involved. It's the exact same car but when speaking "European" Toyota says "AOK" and even has pictures of the Prius towing a small teardrop trailer.

 

If I'm getting mixed messages, I tend to heed the conservative one.

 

When in doubt, follow the manual!