Virtual Categories would give users both options. Using tags to sort by models but all the posts actually exist under the parent and can all be viewed exactly as they are now. I moderate several forums and I have developed a few, I would be happy to filter existing posts into tags although its not necessary needed it would be good for archival searching.
That's Hyundai, No offence but not a lot of DIYers driving Hyundai's. Almost every truck forum out there is partitioned that way. And this forum is much closer in user base to those then any Hyundai.Again, I'll tell you that you would hurt yourself with such a change. The Hyundai forum is partitioned like that and you may get one two or three responses from the members because there are so few who frequent any specific forum.