The Mustang called Maria is the same car as John Wick owns in part 1.
On the first shot of exterior of The Continental shown about 21 minutes in, the words 'Fortis Fortuna Adiuvat' is shown engraved just below the roof. These are the same words that are tattooed on John Wick's back.
When Winston performs an unexpected u-turn, in the Mustang, a pedestrian shouts "hey, I'm walkin here!" This is an homage to Dustin Hoffman's character in Midnight Cowboy.
Winston is seen driving the Mustang Mach 1 (license plate XAB 235) that John Wick owns in the films.