This is a save file as generated by the Dolphin emulator (5.0-12716) with every car, track, and game mode unlocked.

To use it in Dolphin, place it in your Wii save directory. To open it, you can right-click on your Driift Mania game in the list and click on "Open Wii Save Folder".

Whether this save file can be used on other emulators or any real console hardware is beyond my knowledge at this point.