If the save was made for build 12922607 and you are on a newer build (e.g., 14567890 ), the game may:

Steam build 12922607 for My Summer Car, released December 10, 2023, represents a backend update focused on stability. Community resources for this and subsequent builds focus on detailed engine assembly, specific bolt sizes, and advanced tuning to achieve a "deep build" of the Satsuma. View the technical details at My Summer Car - Fast Build Tutorial (FULL TUTORIAL 28min)

: The Jonnez moped and boat saw adjustments to their fuel consumption rates to improve realism.

You can verify the patch notes to see what changed in that specific build.

Avoid .exe files. Real MSC saves are plain text files named defaultES2File.txt or defaultES2File_backup.txt .