Open C:\Users\(Username)\Documents\Eden Games\Test Drive Unlimited 2\savegame
Look for the folder with your character name on it. Copy the contents, and paste it somewhere (the desktop is an easy place to remember).
After that, delete the save, start a new one with the exact same profile name as the one you have backed up, and select it as an online profile. After you get past the intro, and buying a car, the game should auto save. Exit the game.
Once that's done, copy the files you backed up, and paste them into your new save folder in: C:\Users\(Username)\Documents\Eden Games\Test Drive Unlimited 2\savegame\(Profile Name)
You're basically just overwriting the progress of your online profile, with your offline data.
Then you're done. Yes, this works. I've done it 3 times already.
All times are (GMT -08:00) Pacific Time (US & Canada). Current time is 9:46:30 PM