Seeing as we have:
Porsche 996 GT1 Strabenversion
McLaren F1
I feel like it's only fair to include the CLK-GTR to finish off the 90s holy trinity.
Hopefully GT Sport pulls a NFS and lets us create official versions of cars using the regular as a base. Like how you can make a 1997 Longtail GTR F1 in NFS from a regular 1994 F1.
This + the 'extreme' upgrade category could lead to:
F1 GTR 1996 -> F1 GTR Longtail
911 GT1 -> 911 GT1 Evo
Diablo GT -> Diablo GTR
Ferrari F50 -> Ferrari F50 GT
Basically a new and improved version of RMs, this would be a nice get around or PD to implement.
So with that being said the new cars I would like to see are:
CLK-GTR, race or road eve though I prefer the road legal one.
F50 GT
F1 GTR Longtail *Technically not new it was in GT4, but this time it'll be branded as a proper McLaren*
911 GT1 Evo 96 or 97, though I feel like it would be too fast to compete in Gr.3, hopefully PD just uses the PP system like in GT5/6
AMG ONE, even though I doubt it seeing as this car seems like it's never coming out; atleast not anytime soon
Corvette C8
TWR XJ220
Regular P1