[SKAzini]

If it outputs 0, and your player ID is 0, it works?
However, this will set the variable to -1 and then to playerid, so if it says 0 now it works (if you have the player id 0):

pawn Код:

public OnPlayerStateChange(playerid, newstate, oldstate)
{
    if(newstate == PLAYER_STATE_DRIVER)
    {
        OwnerId[GetPlayerVehicleID(playerid)] = -1;
        OwnerId[GetPlayerVehicleID(playerid)] = playerid;
    }
    return 1;
}

Also, you can use this to DEBUG if you haven't done yet:

pawn Код:

new string[10];
format(string, sizeof(string), "ID: %d", OwnerId[GetPlayerVehicleID(playerid)]);
SendClientMessage(playerid, -1, string);

Will output the player ID if it has been saved to the variable.