def vehicles
      @vehicles ||= begin
        _, json = get_json("/vehicles")
        json.map { |data| Vehicle.new(self, data) }
      end
    end
def vehicles
      @vehicles ||= begin
        _, json = get_json("/vehicles")
        json.map { |data| Vehicle.new(self, data) }
      end
    end
Returns Vehicle objects for all vehicles the account contains