It's not a Premium car. Looking at the car list, you seem to be after #864, which is a Standard model; #865 (Subaru IMPREZA Sedan WRX STI spec C Type RA ‘05) is Premium.
As a Standard car, the Subaru IMPREZA Sedan WRX STi spec C (Type-II) '04 can be found in the used car lot on certain days (don't ask me which; no-one has plotted the available days yet).
