A couple of things I have noticed

Are you maybe pressing the Power Button too soon? Before the brake pedal is fully depressed? Sorry to hear that. Very frustrating, especially with such a new car. I only had a couple of incidents, where the car wouldn't go into D, but I think I wasn't pressing the brake pedal firmly enough. Operator error.

Please check back in here after your appt at the dealer, and let us know what they found. I sure hope this Gen4 Prius doesn't start to develop a lot of "glitches."

 

The dealer should put it on their computer and it will show any faults.

[My "guess" would start with the brake pedal sensor (is it the brake light sensor - which failed on mine?) - but that's only a wild guess.]

 

The first one sounds like something to do with the brake light switch, possibly needs adjusting.
The second fault, jumping out of gear is a gear selector switch problem, there was another post on here where the dealer had done some work behind the dash (airbag recall IIRC) and a small piece of plastic had fallen down and wedged in the switch, Has it had the airbag recall done ?

 

My first thought was: "the dealer won't be able to duplicate her problem." But I didn't want to sound so negative.

When I was driving yesterday, I was stopped at the red light, and when it turned green I pressed the go pedal... and nothing happened. So I moved the shift selector into D again and pressed the pedal, but still nothing. Finally on the third try the car started moving.

GLITCHES! I don't understand it, Toyota has been building the Prius for 20 years? Yet we still have these flaws and recalls and glitches?! My personal opinion is the build quality has gone down hill.

 

have them check the 12 volt health as well.

 

@CoastRider i think you will find driver build quality has plummeted over the last 20 years.

 

Here is the other thread: Car won't stay in gear | PriusChat

This is a very good idea, since a knowledgable technician may be able to diagnose the problem by correlating your observations with Vehicle Control History events recorded in the car’s computers.

These events, each with a code like “X0501 Shift Operation without Depressing Brake from Shift Position P” or “X0506 Shift B(S) Operation from Shift Position R,” are recorded with date and time, key cycle, elapsed time, and mileage. Unlike the better-known Diagnostic Trouble Codes (DTCs), Vehicle Control History events do not necessarily indicate a malfunction, just that something happened that one of the car’s computers has been programmed to recognize as abnormal.

These occurrences can be the driver’s fault—for example, one in my car’s memory is “X503 Shift Operation during Ready Indicator Blinking,” meaning that I tried to shift into D too soon after starting—but if an event is logged at about the same time as a malfunction, it may help the technician confirm a faulty component, even if he or she can’t personally reproduce an intermittent problem.

I’d suggest you make sure the dealer reviews these events; in the Toyota Techstream diagnostic software, the log is accessed under Powertrain > Hybrid Control > Utility > Vehicle Control History. You could ask the service advisor to have the technician make a printout of this information for your records.

Good luck, and please let us know how it turns out.

 

When I bought my gen 2 in 2005, one of the dealer employees warned me that the car has 23 computers on board. He really suggested I look at another car. I wonder what he would say now that the Prius is such a hit. 23 sounds like a low number even for back then. Today there's probably over 50.