[WARNING] Running out of gas (Gen III)

Tonight I found that running out of gas in my ZVW30 (2010 Prius) silently switches to traction battery power and then runs it down. You have no indication the car is finally out of gas and running down the last of the traction battery power. The first indication is loss of any traction battery 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 - 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 hazardous event.
​

Absent a return of a Check Engine (CE) to use the last of the traction battery to 'limp to the side of the road mode,' I no longer support running out of gas as "no big deal." In fact, the former behavior of the NHW20 and NHW11, to show numerous error codes but continue on traction battery is a superior safety feature compared to this silent "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

p.s. On the third dry tank, I discovered the arrows in the 'energy display' go away when the engine can no longer run. This is the only indication the car is running on the remaining, traction battery power. You have a couple of hundred yards to perhaps a mile before the 'power steering' light comes on and the car becomes an inertial mass . . . no indication the traction battery is tapped for emergency power.

 

Re: [WARNING] Running out of gas

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

 

Re: [WARNING] Running out of gas

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

 

Re: [WARNING] Running out of gas

I owe you an apology!

I transitioned from a technical answer to a general reply to those who think it is not important ... 'just don't run out of gas.' Had we all been 'face to face,' my body language would have made it clear that the second part was addressing those who would diminish the importance of this safety feature.

Hopefully I've addressed my NHW11, running out of gas experiences. In over three dozen cases, it has been a bit of a 'crap shoot' on how long the car would go before the engine conked out. It was completely unpredictable and ranged from 25-130 miles. But I always had the safety of being able to pull over to a safe place to refuel.

BTW, this also addresses those who would use fuel starvation to stop the engine. The new mode means the car is going to come to a stop and not proceed. Sorry, but I think losing a safety feature because of a few modifications is wrong, just plain wrong.

Bob Wilson

 

Re: [WARNING] Running out of gas

The two times I checked, it showed "0 miles remaining."

Bob Wilson