I remember Ford did an on-line poll for people to choose what would be the best sound. There were quite a few people suggesting alternative sounds. The suggestions ran the gamut. Anything from Star Wars sounds, the sound of a 429 Cobra, a semi tractor, etc... to playing the theme song from Chitty Chitty Bang Bang :-)
I think if I had an electric car I’d want a sound generator on it. I’d also make the sound configurable, like a ring tone.
I’d set up different sounds for different situations. Have one that sounds like a popcorn popper. Or Chitty-Chitty Bang Bang. Or an old steam locomotive. Or a little kid just making a “Ppppppt...” sound.
Could have some fun with that. :-)