No, I don't keep track of that, and I don't have a fixed list of what I want to add in each version and what will be left for later versions.
It looks like this is a difference in the tyre compounds, and nobody knows where in the game data they are. If it was ported to the other regions, it may need rally events and/or licenses to be rebalanced, which is a ton of work.
The RX7 and GT40 are just duplicates of the racecar bodies, the GT40 'Mk3' doesn't exist as it's just another duplicate, and the 323Ci is already in the game from day one with a RM.
Yeah, there are quite a lot of cars like this. It's something I'd like to consider doing, but it'd be a huge amount of work to cover all of them so no promises.