After reading Jim's great suggestion of using rating as a tournament filter, it is now so.
Each tournament will now have two restrictions: class and rating range
This will certainly increase the variance of cars per tournament and force players to expand their play. You'll see the rating range along with the class on bracket detail pages (sidebar). And now cars will be automatically filtered by class and rating when entering cars into tournaments.
These first two tournaments still encompass all cars and all ratings, but tournaments after this first set will vary.
Great idea, Jim, thanks for the suggestion. Definitely something I overlooked while over-thinking the game.