In racesims, for the 24 Hours of Le Mans and sports cars and touring cars, GTR2 is the way to go.
Nearly every one of the cars that took part in the Le Mans races of 1997 through 2019 have been made for GTR2, and car sets for 1995 and 1996 are nearly completed.
Additionally, considerable portions of the fields from the Le Mans 24 hours races from 1964 onwards have been made for GTR2.
GTR2 offers excellent night racing with working headlights and track lights, and allows races of up to 24 hours in duration.
Races are possible with nearly 100 cars, if your computer is powerful enough.
There is no known track length limit in GTR2. There are various versions of the Le Mans Circuit de la Sarthe for GTR2 from 1967 through the present.
There are various versions of the Nurburgring Nordschleife (and Sudschleife) for GTR2.
The longest Formula One circuit ever, the Pescara circuit of 1957, has been made for GTR2, and the over 44 mile long Circuito Piccolo delle Madonie in Sicily, where the
Targa Florio sports car race was held, has been made for GTR2.
The downside to GTR2 is that the AI is not very good, and, while the original game car physics and performance are quite realistic, addon cars' physics and performance tend
to depart considerably from reality.
If you are interested in giving GTR2 a try, I can recommend the original game and the FIA GT 2000-2009, FIA GT 1997, and BPR GT 1994-1996 mods as being the best of the addons
that have been made for GTR2. Sports car prototypes from 1998 through 2005 are available in the SCC Prototypes mod, and prototypes from 2006 onwards are in the GRID mod, alas,
with not at all realistic physics and performance.