VIN decode integration — NHTSA vPIC vs Carfax vs Edmunds?

Three viable sources:

• NHTSA vPIC API — free, US government source. Returns Year/Make/Model/Trim/Engine for any 17-char VIN. Coverage is 100% of US-market vehicles since 1981. No rate limits in practice. Latency 200–400ms. This is what I use 80% of the time. Free + reliable + complete for US.
• Carfax VIN decoder API — paid, ~$0.05–$0.20 per decode at volume. Adds vehicle history, recall flags, prior-damage data. Justified only if you’re selling to used-car shoppers and want to surface “recall: brake recall affects this VIN” on PDP.
• Edmunds Vehicle API — paid, similar to Carfax pricing. Stronger on trim-level option packages (e.g. “2018 Honda Civic LX vs Sport vs Touring”) which matters for some parts categories.

Pattern: NHTSA as primary, fallback to manual YMM dropdown if VIN decode fails or returns ambiguous trim. The integration is a single Magento controller endpoint /auto/vin/decode that takes a VIN, calls NHTSA, returns JSON to the frontend, and stores the resolved vehicle in customer attribute my_garage_vehicles (JSON array) for return visits. Conversion lift in my data: +8–15% on vehicles where the customer pasted a VIN vs picked from YMM dropdown.