When driving in electric only mode in the Cayenne (and Panamera) S e-Hybrid, the vehicle emits a noise to warn pedestrians an electric vehicle is approaching. This is to be compliant with regulations like this USA Federal Motor Vehicle Safety Standards; Minimum Sound Requirements for Hybrid and Electric Vehicles
How to disable the sound
Disabling the sound may break one or more of your local motor vehicle regulations, so do so at your own risk.
Underneath some of the plastic engine covers, on the driver’s side of the engine bay, is a small black box that contains the speaker/sound generator.
- The easiest way to disable the sound-generator is to use the PIWIS diagnostic tool that Porsche dealers have and turn it off in the computer settings.
- The do-it-yourself method
Thanks to forum user Robotpedlr for posting details on this at the Porsche Plugin Forum