[Stinged]

Should work, not tested.

pawn Код:

CMD:vehicle(playerid, params[])
{
    new id, action[12];
    if (!sscanf(params, "is[12]", id, action))
    {
        if (!strcmp(action, "delete", true))
        {
            new yn[4];
            if (!sscanf(params, "is[12]s[4]"))
            {
                if (!strcmp(yn, "yes", true))
                {
                    // entered /vehcile id delete yes
                }
            }
            else
            {
                SendClientMessage(playerid, -1, "Are you sure you want to delete your car? If so, enter /vehicle [id] delete yes");
            }
        }
    }
    else
    {
        SendClientMessage(playerid, -1, "Usage: /vehicle [id] [action]");
    }
    return 1;
}

EDIT: I was posting this before you posted the last reply.