FlatOut 3: Chaos & Destruction Save Game Location
Windows
Steam:
FlatOut 3: Chaos & Destruction save games installed through Steam can be found on Windows here:
C:\Program Files (x86)\Steam\userdata\[user_id]\201510\
Linux
FlatOut 3: Chaos & Destruction save games can be found on Linux (Proton) here:
~/.steam/steam/userdata/[user_id]/201510