The navigation layer (intended to run on the companion tablet) was validated live against a self-serve HERE Base Plan key. Key findings:

• You do not need the commercial “Navigate” edition. The free/self-serve Explore edition

already includes EV routing, real-time traffic, and speed-limit spans in routing.

  Only the turnkey navigation engine / speed-limit warner / Electronic Horizon are Navigate-only —
  and we don't need those; the REST APIs cover it.
* **The speed limit rides inside the routing call.** One routing request with the right parameters
  returns the maneuvers //and// per-road-segment speed limits and names — no separate lookups, and
  it bills as a single routing transaction.
* **EV routing must be calibrated to the car.** HERE's generic sample models ~35–39 kWh/100km and
  roughly //doubles// the charging plan. Tuned to the Aiways U5 (~20 kWh/100km, 63 kWh, ~90 kW
  peak) a Berlin→Munich route came out at **21.4 kWh/100km, 3 stops, ~51 min charging** (vs a
  bogus 39 kWh/100km / 6 stops / 175 min from the generic params). Seed the initial charge from
  the car's live SoC over CAN; capping charge stops at ~80% keeps them in the fast part of the
  curve.
* **Traffic-aware ETA** comes from comparing the traffic-aware duration to the free-flow baseline.

Metering discipline: one transaction = one route. Call per-route or periodically — never per GPS fix (that is the only way to blow the free tier). Free tiers are generous (routing 5,000/mo), and overage is negligible. An offline OSM map-matcher stays as a fallback for speed limits — see speedwarning.