“They” here was you. You did the math. That was a bit ambiguous, sorry.

Journalistic misunderstanding is possible, I guess. There’s no way it’s just a wire to the high-voltage motor output - it doesn’t trickle charge off the grid directly either - although omitting the charging system is arguably more of a wording choice.

Here’s another one where they go into more detail, and even mention the possibility of perovskites independently: https://newatlas.com/automotive/mercedes-benz-solar-paint/

Unfortunately the press release itself doesn’t seem to be accessible, after a quick search.