The error is not a bug – it’s a safety feature. It protects your save file from impossible values that the game’s 2006 engine was never designed to handle.

To resolve the "Invalid Car Heat Value" error, players usually have to perform a "Reset" within the Save Editor:

Now, go dominate the canyons of Palmont City in that police cruiser. Just don't complain when the AI Cross doesn't recognize his own car.