[Centigonal]

Currently mandated - newer electric cars make this noise that I would put somewhere between "future theremin"[1] and "terrifying alien chorus."[2]

[1] https://www.youtube.com/watch?v=6Qe1wuDsXVk

[2] https://www.youtube.com/watch?v=SvX7NnlhiOE

Bonus: Kia's sounds like an ambient synth track: https://www.youtube.com/watch?v=NdZwVJPN0Ow

[xattt]

There are electric school buses in my area that emit the sound of the Montreal Metro when driving at low speeds:

https://m.youtube.com/watch?v=Hu_1JM_UiuA

This is because the manufacturer is based in Quebec.