How to run out of gas

Then I'd never know where the real bottom of the tank is, in case of circumstances where I can't refuel.

Or am faced with serious price gouging. BTDT.

As mentioned very recently, my past cars have displayed fuel gauging differences corresponding to more than 2 hours of driving range, close to 3 hours since I learned hypermiling. That is a huge uncertainty. Commercial airliners, which face vastly larger consequences for miscalculations, routinely land with less margin. Characterizing the real range of a specific car requires intentionally running out, or running low to achieve refills close to the manufacturer's claimed capacity. I do that at a time and place and circumstances of my choosing, well before any urgent situation arises.

 

I'm not following that reasoning, unless you think that forced charging followed by EV mode is more efficient than HV mode.

 

I can understand an argument that says 'easier to get going again,' but I still don't follow why forced charging gets you further down the road. Please correct my following (made up) example:

HV: 38% efficiency to shaft
Forced charging: No more efficient than HV, likely less and with additional conversion losses
EV mode: 95% efficient

 

So you would use up the EV miles, then use Charge Mode to build it back up in case you run out of gas? If that's the goal then it seems like it would be more efficient to simply not drive in EV mode so that the battery remains charged and always available if needed. Of course that means the battery then becomes just a very expensive gas can.

If safety is the concern, what might be better is to not use EV during the first part of the trip, and only turn it on when EV miles = MTH (Miles to Home). If you accidentally run out of gas before then, you will have a full EV charge to hopefully get you to a gas station. If you don't run out of gas before EV miles = MTH, then you can switch to EV and arrive home with zero EV miles remaining which is the goal. Might not be the most efficient way to use the EV miles, but it would give the same safety cushion without having to use Charge Mode.

 

Okay so technically the warning you get is low on fuel, not out of fuel, correct? And you are saying if you get the low fuel warning, to first see if you have some EV miles remaining, if not then run Charge Mode for a few minutes to get a least some charge, so that you can use the EV meter as a makeshift "out of fuel" meter.

That is mystifying though that you get a warning at approx. 1 gallon, but no warning when you actually run out of gas. In my Gen 2 I get a visual and audible warning at approximately a half gallon, then when the gas runs out the dash lights up like a Christmas tree. It was about ten years ago so I don't remember all of it but I seem to remember it turned off the radio and climate control, presumably to conserve enough charge so that you can find a safe place to pull over.

I realize from the other comments there is the opinion to simply don't run out of gas. But for the rest of us who do make a mistake once every ten years or so, a warming light and sound would be appreciated.

 

My one and only experience running out of fuel in a Prius left me with enough battery charge to drive over 0.5 miles to a fuel station. I'm surprised that Bob has net seen the same in the Prime (or more.)

 

What 1000 mile club? I drive 90% of the time 50 miles to an EV station.

I constantly get 110+ mpg now and 1,000 miles tanks. I'm about ready for my maintenance and only filled up 5 times :O

 

Yeah.....I guess the 800-mile club thing is rather passe.

Toyota claims that the Prime has a range of 640 miles.
This, Toyota gleefully points out is far superior to the Volt's mere 420 mile range.
This value is still relevant to those who travel or do not like to refuel (either kind) and it represents a capability that cannot be known for sure without testing.

Range is either relevant or it's not.

 

I'm following now -- thanks for the patient explanations.
I suppose that if I run into this situation I might force charge for a mile or so of range to avoid the 'Prime as a brick on the highway' mode.
More than that would be counter-productive since it would just reduce my remaining range.

I agree with you that most owners will not be quite so informed and the unlucky ones who run out of fuel will experience brick mode.

 

This may be a silly question, but how did you get the 90% (I am assuming it's the traction battery charge) show up in the HV monitor window? I usually see estimated range there in miles.


iPhone ?

 

If you are driving on an empty tank but still have battery left, do you run into the same problems of the car not recognizing a one gallon refill that requires the 12v reset ?

 

Owners manual, page 233.

 

Do note that for a legitimate 800 or 1000 mile club entry, to compete in the same spirit or class as other cars, plug-ins must count their battery as part of their 'tank'. That is, no midroute recharging either.

 

In the last eleven years, I have run out of gas twice in my Gen2.

Both times, the traction battery was able to get me to a gas station.

Although, I heard somewhere, it is not good to let the car run out
because gas also cools the fuel pump.

Does anyone know if this is true? (perhaps a previous debate?)

Thanks, Steve