TDU 2 has a built-in anti-cheat checksum. The Save Editor usually fixes this, but sometimes fails on "Ultimate Edition" modded saves. Fix: Use the "Fix Checksum" button manually under the Tools menu before saving.
Since TDU 2 is no longer supported by Atari, save editors are fan-made and not verified by any official source. Always scan files with antivirus software and avoid shady download sites.
Advanced tools like TDU2 VPE (Vehicle Performance Editor) allow you to modify engine specs (HP, torque), swap drivetrains (e.g., to AWD), and even change car prices to enable "money glitches" by buying cheap and selling high. Where to Find Your Save Files
From memory of community research, a TDU2 save editor typically manipulates: