72116342_Grand_Theft_Wiki__the_GTA_wiki__Description
[Ability] Rare [Code] Vehicle With Bold Print [Description] 
Means that the vehicle cannot be found on the streets, but only appears in some missions (like the Phoenix in San Andreas). Rare vehicles can be saveable unlike unobtainable vehicles.
Difference between revisions of "Special Vehicles" - Grand Theft Wiki, the GTA wiki