The article examines methodical issues of selection of heat insulation materials, their properties affecting energy efficiency, as well as methodical issues of experimental determination of heat insulation properties of the car body. This issue has become recently relevant due to the increased requirements to saving of the fuel and energy resources and to improvement of the passenger travel comfort. Domestic and international regulatory documents are analyzed from this perspective.Contemporary materials used for heat insulation of the car body, methods of determination of the average heat transfer coefficient and requirements to such materials are examined. Review of the test results of the most widely spread passenger cars; the issue is arisen regarding necessity of putting the obtained results of experimental research in compliance with the actual operating conditions with regard to the changes of temperature, air humidity and car movement speed.The article examines in details disadvantages of the currently used standardized method of determination of the average heat transfer coefficient. The issues affecting accuracy of determination of this parameter are underlined, which occur in the experimental research and in processing of the obtained results. Practical use of obtained results for designing of new rolling stock is examined.Ultimately, the authors conclude that the valid domestic standardized method of determination of the average heat transfer coefficient does not take into account the number of important conditions. Examination of effect of these conditions on the results of experimental research allows the authors to make conclusion regarding necessity of review of methodical and regulatory and technical documentation for the test methods.