All of the following tasks must be completed to achieve a 100% completion rating.

Unlockable	How to unlock
Activities	Defeat the CPU or an in-game friend at all activities at least once.
Car Thefts	Deliver all 30 vehicles to the garage.
Flying Rats	Find and kill all 200 pigeons.
Missions	Complete all 90 main story and procedural missions.
Most Wanted	Kill all 30 pedestrians on the list.
Random Characters	Find all 14 random characters and complete their encounter missions (except Jeff, Cherise, Clarence, and Ivan).
Unique Stunt Jumps	Complete all 50 jumps.
Vigilante	Complete 20 crimes.