Yeah! This is fun. What would the "unexpected technologies" be?
Musk wants to sell EVs. To everyone. He has to get the prices down to where they are economically and technically superior to most ICE vehicles. What's holding him up?
Battery costs/performance - but that’s in the "expected" category.
FSD - same thing.
How about paint? It sound like that is a major pain. How about some kind of metachrosistic material that is applied to the body, and can be subsequently "programmed" for the desired color, maybe even at the gallery or by delivery personnel. (I’m currently taking a scuba vacation in the Caribbean, and the color changes that a flounder can make are truly astounding).
Tires. EVs need low rolling resistance. I don’t know enough to make an educated engineering guess, but new materials, designs and tread patterns combined with steering and braking algorithms?
In-cabin active noise suppression? (Better than anyone else's, of course)
Variable polarizing windows?