I read a novel [1] in 1979 with a similar plot. In this book, the attack took place in Hollister CA rather than NYC. It didn't have vehicles being hacked, of course, but traffic lights were hacked and people died. Factory production and medical records were messed up and the hospital's power electronically shut down by the intruder. My point is that the idea of attacking a city through its computer systems is older than most HN readers.

[1] The book is Intruder by Louis Charbonneau. A synopsis is at https://www.amazon.com/Intruder-Louis-Charbonneau-ebook/dp/B... and a negative review is https://www.kirkusreviews.com/book-reviews/louis-charbonneau...