There are four vehicles which can be unlocked.

Vehicle	How to unlock
Denkou QX	Place at least third in Siberia league in Proton Class.
DT Basutan	Place at least third in Siberia league in Neutron Class
Faia VM	Place at least third in Shima league in Neutron Class.
Kan Y	Place at least third in Sunahara league in Proton Class.