The reason I asked is because I'm trying to remember how to reproduce these cars again. They weren't 'sharked' with any external device or software, they were produced in-game by using the games Trade feature and two memory cards. The result would produce a full garage of so-called hybrid cars (together with the FTO LM Edition and the Nismo 400R). I guess it would be called an Easter Egg that the developers slipped in for their own amusment.
I would guess it was a programming oversight.
For instance...
If you purchase via memory-card trade a car with lots of parts, although you pay extra for those parts, they are not added to your shareable "inventory" if you don't own them already. (Background: In
GT1 a part purchased for one car can be used by all instances of the identical model (where prize and purchased versions of the "same car" are actually different models)). In particular, while the part is in effect as long as you leave it there, if you remove it during tuning, it cannot be re-added until it is repurchased. That's a programming oversight. The case of tuned cars being purchased is not handled properly. Since you've paid for car plus parts, the parts should be added to the purchased parts inventory (as peculiar as the part-sharing scheme is), but they are not.
Now, from what you are suggesting, it might be the case that if you put a hard-tuned car in the last slot of your garage, sell it, and then purchase the LM prize on top of it, the parts from the sold car are "remembered", and added to it. Or perhaps it is necessary to win the second car, so that the garage manipulation is not so careful; of course that scheme would not need two cards. I actually find it difficult to think of any possible method which would actually require two cards (as opposed to simply moving your game card to slot 2). Perhaps both purchases need to be done via memory-card trade (i.e. purchase tuned car, sell, then purchase an LM car via trade)--but I would really doubt that memory-card trade would not load the entire entry for all cars. Winning a prize after selling a hard-tuned car in the last slot sounds like the most likely method. It's not unlikely the prize-winning algorithm assumes a zeroed entry and moves in only what it thinks it needs to.
Was this a North American game? There were two versions (evidenced by game shark locations). I've never heard of any substantial differences between the two. Wouldn't it be interesting if fixing this bug was the real reason for the new version?
And, wait, the Nismo isn't an LM car, so that shoots part of my theory. But it is a prize. But you do suggest that some of your "hybrids" are not prize cars. Is that actually the case? All 100 cars are hybrids, but most were not prizes?
I don't know about you, but I very rarely sell a hard-tuned car, so it would rarely be the case that the "sold" entry beyond my garage contained parts which ought to be zeroed. (Sometime I'll check whether in my versions a sale leaves a last entry beyond the garage). Actually, probably it's not necessary to sell the last entry, just that the last entry must be the car you want to "donate" parts. (Compression of the garage might leave that entry beyond it, whether or not it was the car sold). So the case I never encounter is actually "I never have a hard-tuned car as the last car in my garage, and then sell a car; in fact I usually sell the prize I just won".
But, in any case, my theory here doesn't involve memory-card trade.
Another variable might be whether you need to have a full 100-car garage for the method to work. I.e. perhaps a full 100-car garage prevents the correct zeroing of the "just sold" garage entry.
I hope all this helps.
Duh. kg means you are not using the North American version. Roman characters means you must be using the PAL version, I believe.
Wait a minute. Are you sure you never put a GameShark near that game? You have a rather large number of credits.