And I thought municipal golf courses were a strange idea.
In my mind, the archetypal racetrack (for cars) is more of a professional sports stadium than public park, but in Buenos Aires the Autódromo Municipal appears to be open to all drivers [Google Maps].
With credit to Google for the translation, here is the description on the city’s website:
Located in the south of the city (at the intersection of Avenida General Paz Roca) is the Municipal Autodromo Oscar Alfredo Gálvez. On weekends, thousands of spectators from all over the country come to enjoy the skills offered by different tracks. Autodrome has a Picódromo. Anyone interested can register their vehicle in one of the classes and participate in the stings.