Record game version, platform, vehicle condition, upgrades, tires and weather. A result without this context is not comparable.
Use a documented route and repeat runs in both directions when the route allows it. Record each measured run, the measurement method and any interference.
Publish the run count, individual results, aggregation and excluded runs with reasons. Distinguish an official specification, GTALedger test and community observation.
No GTALedger GTA VI top-speed measurements have been published yet. This is the protocol required before a test can support a ranking.