Instead of comparing a single car/track combo at a time, why not providing a simple ELO rating across all tracks/cars that a player used. In other words, a system wide rating for leaderboard challenges. It would create an additional layer of competition, and yet possibly make people purchase additional content. Racing Rating Safety Rating Time Trial Rating Elo Rating Algorithm - GeeksforGeeks
Correct. Leaderboard challenges (or the competition) are fun, but there is no way to see or measure progress or standing across all tracks and cars. There is no "rating: managed for people who like "Time trials".
We have Time Attack Division, and Time Attack Rating, but as far as I can tell these only apply to ranked leaderboard competitions, not standard leaderboards. And that's fine, probably best. Not suggesting it be expanded to standard boards.