The car pieces can be found in Indianapolis, Malibu, Philadelphia and 
Chicago. You can claim the piece even if you don't place in the race 
so take your time to search each of these raceways and find the pieces. 

In Indianapolis, turn around as you go under the bridges and you'll 
find the piece in a corner behind one of the bridges. 

Malibu's was the hardest to find...in the big boulders along the 
oceanfront, there is a little tunnel that takes you to the piece 
there.