I wondered what would happen if I accidentally pressed P while moving. A couple times while not quite stopped at the mailbox, I did this and it stopped abruptly! What if I was REALLY moving . . . tried this in the long driveway. Found that above about 2 mph nothing happens . . . button doesn't light, car keeps going. If I'm down around 2 mph, then it stops. Conclusion is that I don't have to worry about pressing it while going 70. FYI Don
In my generation (gen 3), above the speed where it goes to park, I think it just beeps and goes to neutral.
I have not done that with my Prius, but in older vehicles, the parking pawl vibrates without locking into place. This is probably enabled by bevels on the holes in the locking mechanism. Newer vehicles, I assume, will prevent this happening while the car is moving at a speed which would damage the mechanism.
