Can you re-engage D if coasting at high speed?

Leave it in Drive. You should never coast in neutral.

 

There have been some extensive discussion about using N.
coasting in neutral questions | PriusChat
Personally I never use N. You can balance your throttle position such that you get no regen or power consumption if gliding is your thing.

 

The car won't let you do what would be unwise to do, so yes, you can shift to D at any time you are already not going backwards.

When you are in N (and there is almost no reason to be in N. If your brakes get rusty, you can brake in N to clean them off) all the gears are still engaged, the computers just do not let the electric motors get (or absorb) power.
There is no clutch or torque converter in a Prius, the gears are ALWAYS engaged.

Shifting to D just lets the electric motors provide (or absorb) power as well as the engine. You can't get any regenerative braking in N.

Aside from lower MPG, there is only one down side to N, since the motors can't provide power, they can't start the gas engine. So never let it coast from below 40 MPH to above 45 MPH in N. You can over rev the motors. (You notice that the engine is always on over 45 MPH. The car protects itself when it can)

Toyota Prius - Power Split Device

 

Listen to JimboPalmer.

But the direct answer to your question, from personal experience is: yes, you can shift from N -> D at-speed without problems.

 

i constantly shift from D-rive to N-uetral and back to drive. Not a smart thing necessarily, but i am careful of when i do it and my overall (downhill) speed and closing speed. The only times i really do it is when i am going down a hill and the battery on my Prius is already charged... I drove approximately 100 miles on the return leg from Victorville, CA (Freddy's Hamburgers) to 110/101 via the 210Fwy (mostly downhill) doing just this... N-uetral coasting. Down the 15 Freeway i hit 87mph and then put the car into drive which slows you down and then put shifted into B. I ended up using 1 gallon of gas to go 100 miles.

It is a great way to save on gas since everything is off and you conserve the battery power when you need it. You can't just shift into D-rive and power out of an emergency. Not sure of the danger involved with this? But i can say it is a lot safer than the few times I have done this turn-off-the-engine with my Ford F150 cruising down the 14 Fwy, almost out of gas. In the F150 you loose your power brakes and power steering and pretty much forget using your brakes after the first few pumps. The steering on the F150 without power is like wrestling an alligator.

On my motorcycle i have done the turn off the engine and/or cruise in N-uetral, this doesn't work well since when the transmission and wet clutch won't let you just shift into any gear with out it grinding. I have no problem slipping/dumping/double clutching and power shifting anything that i have driven in the past from a bug, nova ss, 64 ford f150, motorcycles, deuce and a half, 5 ton dump etc.

Remember though if you need to give it gas to run away or put the petal down for whatever reason, you can't instantly do it while in N-uetral. Also if you pick up too much speed at doing excess speed you can get cited by CHP or any copper for speeding. Most cops wait near the bottom or middle of the hill for speeders. Thats a fact....

Lastly coming down Cajon Pass cruising in N-uetral in the F150 i got up to around 85? and then slowed the F* down after the cop flashed me with his lights...

The B works very well for reducing speed without using the brakes down a steep decline after you pick up speed.

 

I'm not even a stickler for coming to a complete stop, from Reverse, before switching to Drive. As long as the kinetic energy is small, there is no more apparent harm in this than in doing the same with a common manual transmission. And my household has never had to replace a clutch in its manual transmission cars, even out beyond 200k miles.

Second reason to switch to N: to get practice, and built up muscle memory, just in case some real version of Sudden Unintended Acceleration ever really does happen, and it becomes necessary to quickly disengage the power source from the drive wheels.

I am still unaware of a SUA event (not pilot error) ever being verified in a Prius. But the pilot error version did happen to me in a prior car, and disengaging the power at the clutch was one of the recovery methods that saved me and the car. Because Prius has no clutch, some other method must be used, and N (via R and its error trap to N) is the quickest path available.

I've shifted my Prius into N many times, then back to D, at all speeds up to my maximum cruising speed of 70 mph. But this is only for emergency practice. For 'coasting', I still leave it in D and adjust the gas peddle for no regeneration.

 

i D the CVT seems to create drag so you can't just go faster without stepping on the gas?

 

A steep enough downhill will gain speed even with your foot off the gas, yes.

 

i have gone down some pretty steep grades and if you really want to pickup some speed in a hurry N-uetral is the ticket. Drive doesn't give you enough speed to carry the momentum forward for an uphill or a flat section.

 

At least we moved from"can't" to "not as much as I desire." So long as you know you will get better MPG staying in D, I am OK with however you drive.

 

On a slightly different note,last nite,I found out one can hit the park button at 65 mph,and after an 'o crap' moment and flashing yellow triangle,I moved shifter to D and all is well.It happened when I went to push auto climate button and another finger pushed the park button right below it.
steve.........

 

Yep!

 

Not sure why you do this, it is really silly.

Keep the Prius in D except when going down steep hills, then you can put it in B if you anticipate a full battery via regen in D mode. That's it. Neutral is not to be used except for what Jimbo already said.

False. It is exactly the same and nothing is "off". The same exact behaviour is had by pushing on the gas pedal slightly so that there are no arrows on the MFD. There is no transmission, no torque converter, nothing of the sort. Everything is always connected, hard connected, together. It is like coming from a horse driven carriage and then trying to make your car go faster by whipping it harder. It does absolutely nothing and the only thing that changes is the possibility of damage.

And then as you mention you don't have the ability to go-pedal out of a situation. Bad idea. Damages to the car can be an over-rev'd MG which is a $4K and up repair from the stealership. Even if you saved $1 in gas, this is a poor choice. But in the Prius, you save nothing because you gain nothing in Neutral.

 

Shifting to 'R' at speed does the same thing -- it detects the error, issues a double beep warning, and immediately defaults to 'N'. No trouble reported yet.

These 'accidental' paths to N are actually faster than an intentional shift to N, which suffers a delay of approximately one second. This normal N delay seems to be a filter to throw out accidental bumps of the shift knob.