World Manufacturer Identifier (WMI) tables change slowly, but they do change: new assignments, manufacturer string updates, and corrections. If you ship a free VIN product, you probably keep a local WMI map so you can sanity-check the first three characters without calling NHTSA on every keystroke.…
A single VIN field can contradict a seller's story. Two cheap checks catch many mistakes: WMI (positions 1-3) and plant code (position 11). Why both WMI points at the manufacturer universe. Plant code is manufacturer-specific. Together they answer "does this VIN belong to the brand and factory…
World Manufacturer Identifier (WMI) lookups against NHTSA vPIC are cheap per call and expensive in aggregate. A marketplace that validates every pasted VIN, or a nightly job that refreshes brand maps, will hit the same three-character prefixes thousands of times. Caching is the right fix. Caching…
The first three characters of a VIN are the World Manufacturer Identifier (WMI). They're assigned through a system run by SAE International on behalf of NHTSA, using ISO 3779 region and country ranges. For buyers, the WMI is a quick sanity check on where and by whom a car was made. This post shows…
