How to transfer vehicles from story to online mode?

The verified evidence describes Grand Theft Auto Online as the multiplayer component of Grand Theft Auto V, detailing its release history and setting in the fictional state of San Andreas. However, the evidence does not include any information about game mechanics for transferring vehicles between single-player story mode and the online mode. This specific gameplay feature is not covered in the provided Wikipedia excerpt, which focuses on the game's general description, development, and setting rather than its interactive systems or player progression mechanics.