The heat value is stored as a single unsigned byte in the car’s structure. Offsets differ between Collector’s Edition vs. standard, and between PS2/PC saves.
If you’re writing your own tool, always clamp:

def set_car_heat(data, car_index, heat):
    if not 0 <= heat <= 5:
        raise ValueError(f"Invalid heat heat. Must be 0-5.")
    # write heat to offset

Applies To: Need for Speed: Carbon (PC) / Third-Party Save Editors (e.g., VLTEdit, NFS Carbon Save Editor) Severity: Medium (Prevents file saving/exporting)

Try NFS Carbon Save Editor v1.5 (final stable) or NFS-VltEd — they have better validation handling.
Some older editors are stricter.

| Aspect | Rating | Notes | |--------|--------|-------| | Error clarity | ⭐⭐ | Doesn’t tell which car or value is wrong. | | Workaround availability | ⭐⭐⭐⭐ | Manual hex edit or car removal works. | | Tool stability | ⭐⭐⭐ | Some editors crash on this error. Use V1.5. |

Many old forums link to version 1.0 of NFS Carbon Save Editor. This version is buggy. You need Version 2.1 or higher (preferably the final release by Voss). The newer versions have automated heat correction. Download from reputable modding sites like NFSCars.net or GitHub archives.