Most conventional-drivetrain cars have power-assisted brakes, with the assist provided by intake manifold vacuum.
The Toyota Prius employs regenerative braking devices to recover the vehicle’s kinetic energy during braking events, but it also has traditional friction brakes for heavy deceleration and to hold the vehicle in position at a stop.
Note that since the Prius engine’s duty cycle is computer-controlled, it cannot necessarily be relied upon to have the engine running during braking events.
So…do the friction brakes on a Prius have power-assist? If so, are they reliant upon the engine’s intake manifold vacuum (provided by a reservoir), or are they assisted by an electrically-driven hydraulic pump (like the power steering)?