Your save data tracks your experience level (0–9). Reaching higher levels provides massive performance buffs, such as +10 to +20 Acceleration per level. The Five Kings:
Losing a 100% career mode file because of a corrupted memory stick is a nightmare. This article covers everything you need to know about locating, backing up, editing, and converting your NFS ProStreet save data on the PlayStation Portable. Nfs Pro Street Psp Save Data
Safety & Consistency
Validation & Backup
If you own a PS3, you can copy the PSP save via USB cable using the "Saved Data Utility" menu. However, the PC method is faster. Your save data tracks your experience level (0–9)