What happens at 43 MPH?

I would like to know this as well. It's bugged me since the day I got the car and noticed it. It continues to re-gen, but almost like it spins up the ICE briefly then it cuts back off.

 

If you are gliding, it is most likely the ICE shutting down (0 rpm). Over 46mph or so it must spin even though no gas is being consumed. Just a guess.

 

Do you think it could be Al Gore recalibrating your carbon foot print?

 

You don't feel it because you are making it happen at speeds below 43mph.

 

Most likely it is the ICE starting to spin, or shutting down, depending on whether you are speeding up or slowing down. At around that speed the Prius needs to spin the ICE to keep MG1 from going too fast. If you transition up and down over that speed the Prius will start and stop the ICE repeatedly, which is not a good thing for mileage. Note that the ICE will not necessarily be burning gas, but it will be spinning.

Tom

 

After a brilliant flash of light and a pair of burning tire marks, you will find yourself in another era...

 

Burning tire marks from a Prius?? THAT would be impressive! One thing I did notice when this phenomena happens, is that the iMPG display will go from being pegged at 100 (maxed out at the top) jump down to around 50 and immediately shoot back up. I would think that if the ICE was being shut off, this would seem kind of odd, no? Maybe it's just one of those weird things that happens, but it is a little pronounced. Picture the re-gen cut out that the 2010 was recalled for, and it's a much scaled down version of that in feel. Doesn't bother me, as I've become accustomed to it. Kind of wish I could hook up the SG and pay attention to it when that happens. Of course, that would be a little distracting and I try to avoid distractions as much as possible while driving.

 

Exactly - that bump you're feeling is the flux capacitor kicking in.

 

If you think about it @ that speed, the engine is providing some drag as it is spinning but not providing any power/torque. Once is shuts down, MG1 compensates and it is that transition we probably feel.
I know as the car gets more miles on it things seem to be less pronounced (breaking in).

 

Mine is dead. I need to find some more plutonium.

Tom

 

In some models (built around 1980s or so), at 43mph the "Selective Pollution Eliminating Enforcement Device" becomes active at which point the vehicle must maintain speeds at or above 43mph but never enter the "PWR" territory of the energy display or else the batteries will suffer critical damage and explode with sufficient force to destroy not only the offending Prius but any other (especially traditional ICE vehicles) in the nearby 50 feet vicinity. I believe that evolutionary nature of this design has mainly relegated these vehicles to the museum or scrap yard.

 

Is this a serious comment? The real answer relates to the ICE spinning up and shutting down.

Tom

 

Yep, Tom is right

 

I'm not 100% sure about the GenIII, but with the GenII, if you look at the MFD closely you can see it. If you are going under 40 mph on electric, and start going downhill, you will start to speed up. When you're coasting, you will be seeing the regeneration arrows. At 41mph (GenII) you will see, for just the slight part of a second, the regeneration arrows change to battery power and then back to regeneration. At that speed (and above) the ICE is spinning, but not burning any gasoline.

 

I said "most likely" for two reasons:

1) I am an engineer, and by nature I hate to use absolutes without a rigorous proof.

2) Prius make all sorts of weird noises, bumps, and thumps. Each poster has his own way of describing them. Usually we can guess pretty well, but sometimes it's hard to say for sure based on a written description.

Tom