Ok, several good points, I won't quote everyone, but to summarize.
@eran0004 Yes, I need to duplicate out all of the other Nascars, I'll do that shortly, should remove, no idea, 20-30 cars from the distilled list. I want to be clear, we should keep all of the 'liveries' in future Gran Turismo game, we just shouldn't count them as unique cars. Toyota, Ford, Chevrolet, make a Nascar (or two?) that'll be 3-6 cars across 1 or 2 years. We know that even each manufacturer is guided by weight and power restrictions, but we must believe there's a slight difference, atleast between manufacturer to warrant each as their own unique car.
@Fgame The Primera / EU is already duplicated, so agreed. March vs. Micra, they look quite different and have very different specification (March is much more powerful, and a bit heavier, check it out). So I won't duplicate it just yet, I'm pretty sure also that the March wasn't released in Australia, not sure about any where else in the rest of the world?
RE: MX-5/Eunos/Miatas, I think its universally known as the MX-5, so I've taken out all identical Eunos Roadsters and Miatas. Happy to consider that MX-5 isn't the most popular form, but its just a case of knowing sales numbers to prove one of the others is more common world wide.
@SuzukaStar Couldn't agree more, I believe I've duplicated them out already.
@Snakebitten Yes, completely right, I've left SRT out. I wonder if I've missed other manufacturers? I'll go through and compare again to Kudos.
UPDATE: I had missed several manufacturers, I had gone through kudos with the number system, Volvo is number 100, but then others come into it, Abarth is 101, DeltaWing is 102, ect, so hopefully I have them all now, going through the list manually to confirm.
RE: the Viper situation, any duplicates I could see are likely Vipers... '99 vs '02 GTS seems like an obvious duplicate, keep the '02 as its premium and newer. I'd almost remove the launch edition '13, but I think its just similar enough to warrant uniqueness.
with regards to #51 vs. #91, I would've initially marked these as duplicates - livery of one or the other. Same year, spec, ect, what makes each unique?
@Grandea GTR Also, as other have said, please give me an example where it is or isn't a duplicate and we can review here.
@citroengt1 Thanks! Added Diahatsu, and yes I'll do that, great idea. I might bold the manufacturer title too, I'll see how I go.