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Heat flow from the roof together with radiation through glass windows obviously contributes in the total heat gained of a vehicle cabin. The contribution is more significant especially hot and sunny weather with little wind. This paper presents a new design for vehicle roofing structure in order to improve its total thermal resistance. Its main concept is to utilize phase change material properties to first trap the heat from solar radiation and then release it back to the environment by means of the naturally favored external convection when the vehicle is in use or during the nocturnal cycle. Experimental and numerical analyses have been conducted to compare the thermal performance of the new design and the normal roofing with different colors. A general mathematic equation system has been derived for the thermal process through the roof. The results show that the new design could effectively reduce the downward heat flow from the roof into the cabin. As a consequence, the cooling load of the cabin could be significantly lower.