It is not a surprise or strange thing in Europe that you heard a strange rocket or rat sound from an EV soon. European Union requires a noise-emitting device (Acoustic Vehicle Alert System, or AVAS) fitted that kicks in whenever the vehicle is driving below 19km/h (12MPH). The intention to make and prevent pedestrians and cyclists from being caught unaware by a vehicle that usually otherwise be silent. So all the cars including those from existing line-ups should include and install noisemakers by 2021.
The rules won’t make happy many people around. The charity Guide Dogs and other accessibility advocates want all electric and other EV’s do make sounds at all speeds, so it will support all kind of people who are blind also.