When you have collected ALL the Rockstar barrels you will be rewarded with $300.
Cars
Win the indicated series race to unlock the corresponding car in Los Angeles Career mode.
1969 Chevrolet Camaro RS SS: Bird On The Line
2004 Ford SVT Focus: Cool Breeze
2004 Ford Cobra Concept: 10 Carat Beatdown
2006 Mitsubishi Lancer Evolution IX: Beach Overlook
Audi R8 (2008 ) Become the Los Angeles City Champion.
BOSS 302 (1969) Defeat Junichi in the "Pumping Iron" series race.
L.A. Police Car Get a 100% completion in Los Angeles.
Lamborghini Miura SV (1971) Win the "Yamagata Duel" series race.
Lamborghini Murcielago Roadster "Dub Edition" (2006) Win the "Toshi Challenge".
Mercedes Benz SL65 AMG (2007) Defeat Rin in the "Gold Rush" series race in Tokyo.
Mitsubishi Lancer Evolution IX (2006) Win the "Beach Overlook" series race.
Nissan Skyline GT-R V-Spec (1999) Win the "Tryout Tournament" series race.
Pontiac Solstice (2006) Win the Tokyo Five Race Ginza Tournament.
Tokyo Police Car Get a 100% completion in Tokyo.
Change Stock Vinyls on Cars
It is possible to put the Trans Am hood bird on another car or the old school Challenger's decals on a new car by doing the follwing. Go to the Vinyl shop and save that car's Vinyl Package. There are 3 slots to save in. Then apply it to the other car via the 'Vinyl Packages' option which is located at the bottom.
Cheat Mode
The following cheat options become available at the 'Options' menu when you collect the indicated number of hidden Rockstar barrels. Activating the cheat will disable your progress in Career mode.
Unlimited Nitro:
Collect 10 barrels.
Never Damage Out:
Collect 20 barrels.
Unlimited Special Abilities:
Collect 30 barrels.
Top Down View:
Collect 40 barrels.
No Police:
Collect 50 barrels.
No Fines:
Collect 60 barrels.
Increase your REP
Method 1: Enter "getrep" at the cheat menu. Method 2: Go to your "GPS" and press "square" and press the following buttons: R, L, Right, Left, X, X then press "square" to take off the legend and you will see your REP going up.