At 60 MPH level cruse, the engine will run all the time. The average power is too high to let the engine stop, so it will have to run non-stop at intermediate power levels.

I imagine the same sort of experience happened when we switched over from horses, although I doubt anyone ever mourned the loss of frequent horse farts or tried to emulate them in automobiles. Oh wait, they did, with ICEs. Apparentely ICEs were just temporary noise maker devices designed to wean us off of horse sounds. I think we’re ready to move on now.

As quiet as possible at all times is my preference. I’ll put in a CD of farting horses if I ever grow nostalgic for fueled ICE noise (don’t hold your breath ).

As for pedestrians, sight works, and for blind folks, all vehicles alreday come with a built in sound warning device called a horn.

On top of this, most current hybrids are parallel systems and the engine directly drives the wheels so the engine HAS to follow the pedal.

The Volt is different, the engine as you well know is not attached to the wheels. I would like to see the engine run at set ‘sweet spots’ in it’s range for maximum efficency. The engine would likely move up or down to the spots in a controlled manner to promote smoothness.

I see no reason why if the sound is perceptable the engine couldn’t drift from a ‘low’ spot to a ‘medium’ spot on acccelleration though.

The sound that we associate with an engine is basically the sound of the fuel being burned and the resulting high pressure air rushing from the exhaust.

Spinning the engine without fuel would not simulate the sound.

I honestly think they are working on making the genset so quiet that sound becomes a non-issue.

Disclaimer: I know absolutely nothing about how gasoline ICEs or how generator-engine interactions work.