My preference would be option B, but keep the same car all season.
Have a mix of tracks where some suit the V8's, others the 4's, and we'll get cars that don't suit the track.
Choose a different car each week, and we'll have all 4's or all V8's depending on the track layout (except for a few like Rob and myself who will choose to keep the same car).
That would kind of defeat the purpose of having a field of different strength cars.