Personally I'm a fan of the Europeans cars too. I just like the European take on handling, where oversteer is OK and it as assumed that the driver should be skilled enough to manage it. All the American and Japanese cars I've ever owned IRL were nothing but horrible understeering pigs. However, there are some very good cars from both those regions. The RX7 and Miata and Ford GT and Corvette come immediately to mind as some pretty amazing machines. But overall, I definitely have an affinity for the way European cars handle, both in real-life and in sims. The whole classic European take on "light and nimble is more important than power" really speaks to me too. (IRL however I wouldn't even consider owning any kind of a classic European car outside certain German ones which I already own. I know too much about British, Italian, and French car reliability... A modern car from one of those regions? Sure, but not anything that we would consider classic.) One of the reasons I avoid Japanese cars like the plague in GT4/5 is because they really do seem "magically good." It's been discussed before, so we don't need to discuss it again here, but that's definitely my feeling about them. They just never seem to do anything wrong. Way too easy and predictable. So I use them only for those events which require them. Once my A-Spec career is complete, every Japanese car will probably go bye-bye.
(Unfortunately PD has removed nearly all the small/tight city tracks that were in GT4. This vastly limits the tracks where, for example, a stock Lotus Elan will be competitive. I would love to see a lot more classic European cars in GT6 (or a GT5 update?) and a return of the tracks where they are best suited. Citta di Arria, etc.)