Get first place in the indicated race in the Proving Grounds Series to unlock the corresponding car:

1969 Chevrolet Camaro Z28: North American Open
1970 Porsche 914/6: European Open
1985 Toyota AE86 Sprinter Trueno: Asian Open
1992 Lancia Delta Integrale EVO: RWD Shootout
1994 Honda Do-Luck NSX: Flyweight Invitational
1995 Toyota Border MR2 Turbo T-bar: Mid-Engine Challenge
2001 Mazda Mazdaspeed Roadster: FWD Shootout
2003 Renault Sport Clio V6 RS: Hot Hatch Runoff
2004 Honda Wings West Civic Si: AWD Shootout
2007 Shelby GT500: Heavyweight Open