So based on the Manufacturer Points system found here
https://www.gran-turismo.com/gb/gtsport/fia2018/detail/ and a look through each region leaderboard I've got the standings after Round 1 as;
1. Nissan - 125 points
2. Ferrari - 108
3. Porsche - 99
4. Mercedes - 78
5. Lexus - 72
6. BMW - 68
7. Ford - 65
8. Mitsubishi - 59
9. Dodge - 56
10. Subaru - 52
11. Chevrolet - 46
12. Aston Martin - 46
13. Toyota - 45
14. Honda - 44
15. Mazda - 36
16. Hyundai - 33
17. McLaren - 27
18. Jaguar - 26
19. Citreon - 22
20. Renault - 17
21. Audi - 17
22. Alfa Romeo - 16
23. VW - 14
24. Peugeot - 13
25. Lamborghini - 10
Obviously only 1 round in Gr3, more rounds with both Groups to be more representative. Suzuka is by far the weakest Renault track and that bloody Megane Trophy will eat up points

, Tidgney had an off race in the Pug so that threatens to climb as well along with Hellzfire in the Citreon.