Sorry to doubt you, but were you looking at the ground? Did you ACTUALLY SEE the car move? Or were you looking inside the car, and your inner ear "told" you that the car moved.

I fly a bit (not ride as passenger, fly) and I am familiar with the sensation of "apparent" motion vs ACTUAL motion that the inner
ear frequently causes.

The Prius uses the drive motor as a starter motor, and the car can REALLY rock back and forth a couple inches when the gas engine kicks in (while the car's parked). Kind of like the kick from a impact wrench firing.

Due to the nature of my hobbies, I spend hours at a time with the Prius parked and in "idle" mode. Even though I know it's an Illusion, I could SWEAR that the car lurched forward when the gas engine kicks in.

Just asking....