Literally no product you can buy would meet this definition.
I guess you could make a brutalist city bus?
That is a peculiar way to describe what Brutalism projects. I've always thought that it projected the sinister power of bureaucracy, and that was why government officials fell for it as hard as they did.
(I know you're just quoting the author.)
By the express wording of the quote, it doesn't describe what Brutalism projects but what Brutalism was meant to project.
Brutalist comes from the french "brut" meaning "raw". So a car could perfectly well be brutalist by not hiding its nature under paint and covers.
The unpainted Reventon replica[0] is conceptually closer: it's bolted and welded sheet metal, and that's left obviously visible.
[0] http://www.gadgetsandgizmos.org/man-builds-replica-lamborghi...
I find this definition the opposite of pedantic, paying attention to the spirit of the thing rather than the smaller details. Brutalism is not really a style for personal cars, and certainly the entire Elon Musk saga is non-Brutalist as you can get.
If we remove the requirement about the concrete, then Geoff car would also tick all of the boxes: https://www.youtube.com/watch?v=PCSNCs7bwCw