[WARNING] Running out of gas (Gen III)

[bwilson4web]

Tonight I found that running out of gas in my VZW30 (2010 Prius) completely removes all traction battery power. There is no motive power to get to a 'safe place' to refill. I was able to coast to a parking lot but basicly:

• power steering failure icon - this is the only warning light, IMHO, totally inadequate
• all power indications 'off' - it is as if the car had been shifted into "N"
• shifting to "N", stays in "N" and does not return to "D"

I can buy a new traction battery and have no problem with being put in "EV" mode. But the car would not shift into "D" nor respond to "EV." Compared to the NHW20 and NHW11, this means a valuable safety feature has been lost.

Trying to run out of gas, on flash, the first time it went:

• 122.1 mile
• 56.6 MPG
• 2.156 gallons, 1.6 gallons in handbook

The only indication I got of a problem was "electric steering error" icon flashed up. Not sure what it was, I was going down hill and pulled over into a parking lot and put my spare gallon in. The error indication cleared and I was off to fill-up.

Second running out of gas on flash, it went:

• 132.6 miles
• 60.8 MPG
• 2.18 gallons

However, this time I had just crested a slope on a limited access road with no shoulders. Fortunately, I had momentum and coasted off the road into a parking lot. Had there been stopped traffic or other hazards, I would have been in a four-lane road, 50 mph (80 kph) with a car totally inert:

34 40' 13.35" N 86 34' 25.67" W

You'll notice this is on a limited access highway just as I was approaching a merge lane for traffic from Martin Road. During rush-hour, this area is 'stop and go' and having the ability to move through traffic, even if limited EV mode, would be the difference between a safe and very hazardous stop.

Absent a return to a 'limp to the side of the road mode,' I can no longer support running out of gas as "no big deal." In fact, I believe the former behavior of the NHW20 and NHW11, to continue on traction battery, to be a superior safety feature to this "coast to a stop NOW!" behavior:

• I can buy a new battery even if I damage it getting to a safe place, off the highway.
• Dead because my Prius stopped on an unsafe place and an accident occurred, it would be hard for the dead guy to buy another Toyota battery or Prius. The accident rate for the Prius would go up and potentially, the insurance rates rise. Worse the Prius will lose the justified reputation for a safe vehicle.

Bob Wilson

[damack1]

Bob,

I agree that this is a safety concern. On the other hand, running out of gas is entirely preventable. In my 40+ years of driving, I have NEVER run out of gas. My practice is to always gas up when I get to 1/4 tank.

Is there something about the Prius gas gauge that makes it less informative, so we can't quite tell if we need to gas up? I'm not being sarcastic: I don't have mine yet, and I have noticed threads that seem to indicate that it's difficult to determine how much gas you have and how far you can go on it.

[timberwolf]

I appreciate this discovery has come as a shock to you, and in your eyes this is a step back from the Gen II, but I don't see this as being any different from running out of gas in a conventional car. I would guess thousands of motorist run out of gas in conventional cars and they don't all die in horrible accidents.

[bwilson4web]

Originally Posted by damack1

. . .
Is there something about the Prius gas gauge that makes it less informative, so we can't quite tell if we need to gas up? . . .

The absence of a bladder suggests the fuel indicator is more accurate than it was with my NHW11 and the reports on the NHW20. That in two fuel exhaustion tests, the remaining fuel values are the same with a very small error, 2.16 vs 2.18 gallons, suggests we can trust the fuel indicator.

Until we get a return of "limp to side of road" mode, even EV limited to 9 mph would be enough, running on flash is risky. It is too risky for me to feel any need to replicate this experiment with one exception. I did not try to turn off the car and then power it up again and hit "EV" mode. But having to do this cycle in the middle of traffic is nuts compared to just switching into "EV" mode and a 'host of errors.'

Properly designed, I would like to see:

• turn on hazard lights - automatic when the fuel runs out, let the operator turn them off but put them on automatically
• fuel oriented flashing lights - all fuel level bars flash ON/OFF
• 9 mph EV mode - this at least lets the vehicle reach a shoulder or safe parking area

I can replace a battery, replacing a life is a lot harder.

Bob Wilson

[wvgasguy]

It sounds like we have enough data to simply realize that when we're "empty" we still have approximately 2 gallons of gas or about 100 miles to fill up. That should be enough miles for anyone to find gas or a place to pull over and stop.

If many people are unintentionally running out of gas then they need to develop a reserve like on my seadoo. That is you have to turn a knob to access the reserve. That way it's always there when you need it.

[JimboK]

I'm guessing they designed it this way to help protect the battery after some folks have killed their battery by running on it for an extended period.

I'm with Timberwolf -- it's no different than most every other car on the road.

[Rokeby]

Bob,

IIRC, on the Gen II, there is a all too brief flashing notice of low fuel
sometime while one pip is showing on the guess-gauge. Far too little
notice in my opinion. ( I'm a "fill up at two pips" kinda guy. Haven't seen
only one pip yet.)

Has there been any change in this irksome detail in the Gen III?

[bwilson4web]

Originally Posted by Rokeby

Bob,

IIRC, on the Gen II, there is a all too brief flashing notice of low fuel
sometime while one pip is showing on the guess-gauge. Far too little
notice in my opinion. ( I'm a "fill up at two pips" kinda guy. Haven't seen
only one pip yet.)

Has there been any change in this irksome detail in the Gen III?

In over three dozen 'running out of gas' events (planned) with my NHW11, I found:

• 130 miles - longest distance on flash (the first)
• 65-70 miles - median
• 25 miles - shortest (occurred while merging into traffic on a limited access highway ... I simply went on battery to a safe shoulder about 150 meters down the road)

That is the simple technical experiences I've had. Understand the following is a general answer, not specific to anyone, to those who may think the answer is to "never run out of gas."

I consider having an automatic EV mode when the engine runs out of gas just like having a seat belt when having an accident. Sure it is easy to say, "Just don't have an accident" but that is not always avoidable.

I don't care if someone else never has to use their seatbelt or air bags. In fact, it is a good day when no one has to use their seatbelt or air bags. But there is no reason for a $24-30,000 car to "protect itself" by stopping in the middle of a hazardous highway or traffic situation instead of using that marvelous traction battery to at least make an effort to get to safe place.

The issue is black and white:

• Save the hardware?
• Save the human?

Those who say, "Just never run out of gas" are echoing the old refrain, "Never have an accident" or "Never be unlucky." Tools serve the man and the accident that kills the out-of-gas driver will also destroy the out-of-gas but fully capable Prius with a charged traction battery.

Before safety interlocks became popular, any manual transmission car could be moved out of traffic by:

• put in first gear
• turn the starter

You won't be going anywhere fast but if you are behind a blind corner, you can get to a shoulder or out of the way so you won't be hit. The safety interlocks are there so folks won't drive through their garages (aka., see "Car Talk".) IMHO, hitting "flash" should disable these interlocks so people could use the starter motor to reach a safe place.

Bob Wilson

[Rokeby]

Bob,

My previous question was purely information seeking and technical in
nature. It was not meant to be a goad, or otherwise diminishing to your
underlying concern about safety of human life.

My most sincere apology if I came across as insensitive or flippant.

[steve44]

Who runs out of gas? I always thought that was a myth!
Seriously though, stop running out of gasoline. It IS extremely easy NOT to run out of gas. If you think it's like trying to avoid an accident then you're insane and probably rely on others way too much. Sack up and take responsibility so you don't cause somoene else to hit you on the highway. You're driving dangerously.