The % levels - did you go back and win all the trophy cup challenges? You have to play each track like 3 times in order to get everything. Hope these answer your questions.
Play as Jiminy Cricket:
Collect all the parts of the Firework Machine.
Play as Ned Shredbetter:
Successfully complete the Trophy Challenge.
Play as X.U.D. 71:
Collect all eight fairies on each of the following tracks: Tomorrowland Speedway, Space Mountain, Blizzard Beach, Dinosaur, Pirates of the Caribbean, Jungle Cruise, Splash Mountain, Haunted Mansion, and Big Thunder Mountain Railroad.
Splash Mountain track:
Win all nine first place pennants.
Hint: Spin out:
Hold R1 and press Left or Right. Your car will go in a circle and the back tires will smoke. The smoke will turn green, then pink, and back to green. After the smoke changes three times the car will spin out of control.