Grand Theft Auto IV Guide - 100% Completion Requirements
If you have completed the game but have not scored 100% then one of the items below is probably the reason why. Make sure you have done all the stuff below if you want to complete the game 100%.
Complete all 94 missions.
Deliver all 30 of Stevie's text message cars.
Complete all 10 of Little Jacob's drug deliveries.
Complete all 10 Exotic Exports for Brucie.
Win all 10 of Brucie's races.
Complete all 9 assassination missions.
Unlock friend special abilities (Roman and Dwayne excluded).
Win every activity (full-game of bowling, darts, and pool) against a random computer opponent or friend once.
Beat the QUB3D high score (at least 11,000 points).
Take friends to every activity available via their Phonebook menu (Roman and Dwayne excluded).
Meet random characters and complete their tasks (Ivan, Cherise, and Clarence excluded).
Kill all 30 criminals on the Most Wanted list (via police car computer).
Complete 20 Vigilante missions (via police car computer)
Kill all 200 flying rats/pigeons.
Complete all 50 stunt jumps.