In this save you get the upcoming DLC, the save includes:
Dodge Viper SRT10 ACR
Mercedes Benz SL 65 AMG Black Series
Nissan 370Z Nismo
Ford Mustang V6 Premium
Ferrari 458 Italia
How to use:
First change the ID's to yours then rehash and resign.
Then move to your memory stick.
Once your have your memory stick plugged in to your Xbox COPY the save to your HDD.
Then play from your HDD, if you come of the game you have to copy the game to your HDD again or the cars will just come up as pink mustangs.
Note: Delete any DLC cars or it will overwrite the modded cars. You will spawn in the used car dealer ship, leave then go back in then buy the car from the guy at the desk and enjoy.