The Proto Motors Spirra is there in the American and PAL versions from Day 1 as I bought it early on the American version so that I could take a picture for my site (back up a level from the new Korean cars and down to the American, PAL and Korean page).
The Japanese version has 710 cars. The American version has 721 cars (loses the Mini Cooper 1.3i and Ultraflo-Esso Supra). The PAL version has the most cars 729 (again loses the Mini Cooper 1.3i but retains the Ultraflo-Esso Supra it also gets all the Vauxhalls). The Korean version has 725 cars (again no Mini Cooper 1.3i as that is only in the initial release of the game in Japan etc).
The new cars in the American game cannot be used in a LAN game linked to the Japanese version, so I assume they are not there... the game locked. I have not tried the old Mini in a linked game or the new Korean additions. I think I hear rumours that the Spirra was originally going to only be in the Korean version. I'll see what happens with the extra Korean cars on a link-up to the American version.
There is really no definitive version of the game, but the Korean version is I suppose the closest.
