How to access the vehicle menu in gta online?

The single source supplied is a Wikipedia article that describes Grand Theft Auto Online as an online multiplayer action‑adventure game and lists its release dates and general gameplay features. It does not contain any information about in‑game menus, controls, or how to access the vehicle menu. Because the evidence is insufficient, I cannot provide the requested instructions. For accurate guidance, consult the official Rockstar Games support pages, the in‑game help menu, or reputable gaming community resources.