"Rapid shift to N accepted!"

I have no answer to any of your questions. But it sound interesting enough to follow the discussion.

I've never seen that message on my PRIME, but I've had trouble placing in N while stationary at a car wash. So, after you got your car shifted to N at 30mph, were you able to bring back to D without any problem?

 

I shift to N at speed to activate "glide" from the "pulse and glide" gas saving technique. Gliding is more efficient than keeping it in D and letting it regen IF you have enough room to glide without having to stop or slow down quickly. I don't touch the brakes until I shift back to D and use regen braking.

I have noticed that I can usually rapid shift to N, except when stopped, but I don't know the specific conditions. It's not really addressed in the manual.

 

You can slow shift to N also, to avoid the beep (just hold the stick longer in the N position). Also, it's not just an ICE vs Electric question, the act of slowing down with regen recoups maybe 20% of the energy, while letting it just glide in N lets you use closer to 100% of the energy you used to pulse (accelerate).

 

How much regeneration is the car doing when coasting in D with both pedals untouched? I don't have the same model as you, but I get the feeling that there aren't a lot of savings to capture with all that effort.

 

This "Rapid Shift" message is newer than my Gen3, so I can't give a complete answer for Gen4. But will address some other portions:

Do you remember the Toyota Sudden Unintended Acceleration scare and hysteria nearly a decade ago? Similar to the runaway Audis a couple decades earlier? People were experiencing alleged runaway cars with surging engines. Shifting to N is one way to gain control of such a runaway vehicle. The ease and intuitiveness of shifting to N in manual transmissions is one reason why manuals are far less frequently involved in SUA-type crashes than are automatic transmissions.

At speed, my Gen3 will instantly shift to N if I push the shift lever to R. This is because it recognizes highway speed R as an error, so defaults to the safe choice of N, while giving a double-beep warning. Does your Gen4 issue the same double-beep as my Gen3, or does it give this "Rapid shift accepted" message instead?

I occasionally practice this at-speed R shift as a faster path to N, just in case I ever need it for an SUA incident.

 

Never heard of "rapid" shift. I wonder if it detected an "illegal" shift attempt (ie it thought you'd tapped it to go to R?) - and moved to "N" which is a fail-safe position for many illegal movements?

Or maybe not. Have you been able to check the Data Log?

 

The Electronic Shift Lever Control topic in New Car Features (more info) mentions this behavior but doesn’t explain the reason for it:

(6) While the vehicle is being driven at a certain speed or more, the shift state can be changed to neutral (N) without having to hold the shift lever in neutral (N) for a certain amount of time. In this case, the buzzer in the combination meter assembly sounds (once), the master warning light blinks and a confirmation message is displayed on the multi-information display.​

The Repair Manual says a Vehicle Control History event, “Quick Shift Operation to Shift Position N during Running” (X050A), is also recorded.

I checked FMVSS No. 102 and SAE J915 and didn’t see anything requiring this behavior; I think @fuzzy1's explanation is as likely as any. It might be worth searching the patent literature, I suppose.

That’s a different one, “Shift R Operation during Forward Movement” (X0508).

 

... depends on how fast you're going - I had a deserted road, I realised I had an intersection in a couple of kilometres so left it in D, no pedals - and it increased 2 bars from 100 down to about 30. But I can't recall what incline it was, slight downhill I think. I only had 3 bars of battery.

And, of course, counting bars is very inaccurate - it could be showing 3 bars, but almost 3 - or almost 2.

 

... and different bars have different sizes too.

 

Not that I drink - or know where "Put-In-Bay" is ...

 

Strikes me that it's worth monitoring with a scangauge or the like to put some real numbers on it. Might help put it in perspective vs. the added workload/distraction.

I reckon there's a familiarity to it as well. In traditional cars where neutral physically disengaged the engine from the wheels there were much greater savings to be had. That's something I did in old cars.

Personally, I've long since retired the technique of using any form of neutral on a public way on the grounds of safety. I don't like adding steps before I can take positive control of the car when reacting to a surprise. No big deal on a track, but I no longer risk it in public.

Both my wife and I did not like the information content vs. screen space quotient of the "bars" display, so we banished it for the simple display. Fuel level, clock, instant MPG and outside temp.

 

I don't need all the fancy screens now I'm used to driving a Hybrid.

The HUD shows:
, so I've got the 8 bars - if I look - it's sometimes handy if I'm looking to get a better l/100km. I think I can change the HUD to only show the speed.

On the main display, I generally have this display - which isn't distracting at all: