VIN and year rules

HW Check is conservative. If a year is a known mix, the result is uncertain.

• 2024+ Highland Model 3: generally HW4.
• Pre-refresh 2017–2023 Model 3: HW3 (2017–2018 called with medium confidence; verify HW2/2.5).
• 2020–2023 Model Y: HW3. 2024 Model Y: uncertain. 2025+ Model Y: generally HW4.
• 2021–2023 refreshed S/X: generally HW3. 2024+ S/X: HW4 at medium confidence.

VIN decode uses the public NHTSA vPIC API (no key). It returns make, model, year, and trim when the service answers. A VIN does not reliably encode Autopilot hardware, so the same year rules still apply. If NHTSA fails, the 10th VIN character can still yield model year, and the year/model form still works.