Gotta luv dem rear spoilers, they work so well at illegal speeds! I imagine that this car, prior to its impact modifications, could get 170-190 in straight-line speed but that is not NYC at any time!
On a related topic, there is a new Cannonball record for NYC to LA, doing ~2,800 miles in 26h38m (106mph average) using the pandemic-emptied roads to beat the old record of 31h04m (90+mph). This record was set using an Audi A8, a significantly cheaper vehicle to this totaled Porsche!
I believe the top speed on those is well over 200mph.
Yes, the spoiler does work at high speed, and these cars were capable of over 200mph.