What is the Speed used for the ETA and the Isolines calculation? (Cars and Trucks)

Here you have a summary that explains which speed is used for cars (first image) and for trucks (second image) when it comes to the calculation of ETA and Isoline.





Please also keep in mind...

Regardless the time when the route starts, Real Time Traffic (RTT) will be used (if available) for the stretch of the route happening in the present. Example, calculation request for a route that started 2 hours in the past which lasts ~5 hours. HERE will use RTT for the third hour of the route.
Any time RTT is supposed to be used, but for whatever reason not available, HERE uses pure Traffic Patterns (For day of the week and month of year with 15 minutes granularity. Holidays pattern applied for the countries where available)
Any time Traffic Patterns is supposed to be used, but for whatever reason not available, HERE uses a speed value calculated from combination of Functional Class (FC), Speed Category and country.
Free Flow Speed from traffic Patterns (When FC is 1 to 4) is the best speed of the day for a given segment. For FC5, speed value is calculated from combination of Functional Class (FC), Speed Category and country.
* Please note that the natural evolution of the routing engine could make this current behavior be different in the future. This KB will be reviewed in the future to keep it updated to the latest changes.