I managed to find another useless innovation: we all know the reverse warning signal, short beeps indicating a big truck is reversing (with no rear vision at all). That’s very useful and people are used to it and act upon it.
In the early 80s Toyota innovated the reverse warning signal and equipped their MarkII with a spoken reverse warning signal:
Of course this innovation is only useful for people understanding Japanese, if they are used to it at all… If someone would reverse with their Jaguar and that car would tell me in English “Watch out, big lump of iron is reversing! Keep away! Do not stand in the turning circle! Etc. etc.” I would not really act upon that: I’d probably first start laughing my ass off and then probably congratulate the driver with such cynical car!
You see, that’s why this can only fall into the category of useless Japanese car innovations!