afaik they are running as the slower class Group N (National Group) in the Spa 24hrs. The Huracan Super Trofeo also can race in Group N in the 24h race. But there are rarely entries.
Spa24h has 4 groups containing GT3 cars plus the Group N with cup cars.
The 4 groups are PRO, PRO-AM, SILVER and AM (Gentlemen drivers)
Overall rules: max 14hrs for a single driver, 65 minutes maximum for one stint and maximum of 3 stints in a row for one driver.
- PRO: maximum 3 drivers on the car. FIA driver classification is not important. Driver times have no limitations except the overall rule. Number plate: Black number on white background.
- PRO-AM: maximum 4 drivers on the car. Minimum of 2 Bronze rated drivers in the team. With 4 drivers the highest constellation is 2 Platinum and 2 Bronze drivers. One of the Bronze drivers must drive at least 8 hours total. He must drive at least 1 hour in every quarter of the race . Number plate: White numbers on black background.
- SILVER: 3 or 4 drivers on the car. they all need Silver rating, exceot when there are 4 drivers, then 3 silver and 1 bronze are possible. Other than that the PRO rules apply here too. Number plate is like in the PRO class.
AM: it's the class for the gentlemen drivers. therer must be 3 Bronze rated drivers in the team, but a silver rated driver can complete the team as a 4th driver. so maximum is 3 Bronze and 1 Silver. The silver rated driver is not allowed to drive more than 2 hours in each quarter of the race, and not allowed to drive more than 6 hours in total. Number plate: White number on red background.
National Group (Group N): It's for cars of single make cups like Porsche GT3 Cup or Huracan Super Trofeo. Number plate and rules like the AM class.
In ACC you also get a rating and also see in which class you are driving (PRO, PR-AM, SILVER, AM) when you look at the car numbers at the timing boards where you see like white numbers on black background etc.
But ACC does not replicate the real life rules 100%, unfortunately.
From the ACC forums:
Case D Sprint races ( two one-hour races)
- A mandatory pit stop for changing drivers and all 4 tyres is to be carried out during each of the 2 races. The car must cross the pit entry line from 25:00:00 after the Official start of the race until 34:59.99 after the Official start of the race. Only one driver change may take place during the race. Any pit stops taken before the start of the pit window will not count as the mandatory pit stop. ( this is ok in game)
- 37.2 Refuelling for events run according to Case D
Refuelling is forbidden during the races and in the qualifying practice session. ( this is ok in game)
3H races
- There will be two mandatory pit stops. During each mandatory pit stop the car must be refuelled and all four tyres must be changed. At each mandatory pit stop, there must be a change of driver. ( this is ok in game)
- The maximum stint length from any driver is 65 minutes (one hour and five minutes). ( this is ok in game)
6H races
- It is not mandatory to change driver or to change all four tyres at each pit stop. ( not in the game)
- The total maximum time per driver is 140 minutes (two hours and twenty minutes). ( not in the game)
- The maximal duration of a driving stint will be 65 minutes. ( this is ok in game)
24H races
- It is not mandatory to change driver or to change all four tyres at each pit stop. ( not in the game)
- The maximum continuous driving time per driver is three hours 15 minutes. After this period, a minimum rest period of one hour is required. No driver can drive more than 14 hours in total. ( not in the game)
- The maximal duration of a driving stint will be 65 minutes. ( this is ok in game)
https://www.assettocorsa.net/forum/...es-rules-and-participants.59102/#post-1073083
ACC Blog:
https://www.assettocorsa.net/forum/...cpain-gt-series-rules-and-participants.59102/
I don't think that these things changed in the meantime.