Hmm, never saw any in CTSCC so that's probably why I didn't know. Need to start paying more attention to PWC.
If you can find a way, or can just pay for the app (think there's a free trial), I recommend watching the GT4 and TC races from last year. The grids weren't massive, but they were quite diverse, and some of the battles were really intense.
In GT4, it was the Blackdog Camaros and Roush Mustangs, Maseratis and Aston Martins vs the lightweight KTMs, Sin R1s, G55s, and Evoras. The dynamic between the heavy and light cars - heating the tires, tire wear, performance at different parts of the lap - made for racelong battles that came right down to the wire.
The TC class was just as good. BMW M2, Honda Accord, MX5, 370Z, and a few others. Again, the fast, heavy cars like the M2 and Accord fending off the late charging, lightweight MX5s. A couple of the guys in the MX5s really drove the wheels off them at different points in the season, and Nick Wittmer in the Accord was really entertaining all season long too.
I think in GT4, grid size is expected to grow this year, which I'm really looking forward to (it actually grew significantly over the course of the season last year...compare COTA to Leguna Seca, it's night and day). Hopefully the TC class grows too.