You have to complete every race in the championship, not just one. If you drop out of the championship your progress is lost and you have to start from the beginning next time.
Even if you have won 5 of the 6 races and quit the 6th you have to start again i tried it with B-Spec FGT quit the last one as i had won the first 5 and was NOT award the Championship i had to endure another 6 hours of more Bob time !
If you want to skip the last one, you still have to start the race then exit for it to count. Don't quit at the race start menu or you'll have to do the whole thing again.
If you want to skip the last one, you still have to start the race then exit for it to count. Don't quit at the race start menu or you'll have to do the whole thing again.