Win the indicated Bonus Part Challenges to unlock the corresponding Super Composite hood and spoiler for the listed car:

Carrera 4S: Bonus Part Challenge 1 and 2 on Rank 5
Carrera GT: Bonus Part Challenge 1 and 2 on Rank 2
Cobalt SS: Bonus Part Challenge 1 and 2 on Rank 13
Corvette: Bonus Part Challenge 1 and 2 on Rank 6
Eclipse: Bonus Part Challenge 1 and 2 on Rank 11
Ford GT: Bonus Part Challenge 1 and 2 on Rank 3
Gallardo: Bonus Part Challenge 1 and 2 on Rank 4
Golf: Bonus Part Challenge 1 and 2 on Rank 15
Lancer: Bonus Part Challenge 1 and 2 on Rank 9
Mazda3: Bonus Part Challenge 1 and 2 on Rank 14
Mustang GT: Bonus Part Challenge 1 and 2 on Rank 10
RX-8: Bonus Part Challenge 1 and 2 on Rank 12
TT: Bonus Part Challenge 1 and 2 on Rank 7
WRX STi: Bonus Part Challenge 1 and 2 on Rank 8