Help needed!

No gear changes in a Prius. There is a slight stutter to the engine when it comes on, and that may be what you are feeling. The engine is often turned off at a stop. When you pull away, the initial acceleration is from the electric motor, and then the engine kicks in. A minor vibration at this point is normal. It shouldn't be a continuous vibration.

Tom

 

The engine starts as needed:
1. recharge the traction battery
2. add torque to help accelerate the car
3. provide heat to the passenger cabin
4. when moving faster than about 45 MPH

1 and 3 can happen at any time. 2 is likely when the driver presses the gas pedal. 4 happens to prevent damage to one of the electric motor/generators.

The computers take care of all of this, nothing for you to worry about.

 

With a warmed-up engine and nothing unusual, the engine will have stopped well before the car stops. No need for power during deceleration, and the gas engine can go to exactly zero rpm once road speed is below a threshold in the high 30s mph.

However, many new Prius owners are surprised to feel a "stop shake" at a stop light or such something like a couple of miles after startup. This is indeed the gas engine stopping, and can be a surprise because the display in this case does not appear to be showing the engine as on, just before. The answer is that the display arrows only show intentional energy provision by the gas engine (either electric or direct coupled mechanical) and not the cases where the engine is operating for other reasons (such as warming itself and the catalytic converter...).

Pilots have a pair of sayings about the (highly automated) Airbus as commented on by flight crew of varying levels of experience:

Newish AB Pilot: What's it doing NOW!.
Experienced AB pilot: It does that sometimes.

Seems to apply to the Prius. It is definitely more noticeably autonomous than other cars I've ever driven.

 

Let's just say this 'stuttering' in the Prius drivetrain is still something Toyota haven't 'perfected' yet.

Or Toyota may claim this is a 'feature' and not a 'bug', because they want us (the owners) to know the engine has been shut off (or startup). That's ok, no big deal as long as the car always run with high MPG.