Another car I suggest talking about would be the Slamvan or Remmington, loads of people ask about this in many different threads:
Slamvans (Required for Export/Import)
Spawns behind the Adult Shop in Los Santos, ONLY WHEN ITS ON YOUR LIST FOR EXPORT!, also it roams the streets of San Fierro.
Remmington (Spotted rarely in Little Mexico in LS) also seen alot on SF.
Hope I could have been of some help.