Hybrid cars were developed and are widely utilized in developed countries due to their sustainability advantages. However, developing countries were seen to underutilize this product where research showed that the economic, societal, and environmental concerns were considered by consumers. The current study aimed to assess the behavioral intentions for purchasing hybrid cars with the use of an established new framework called sustainability theory of planned behavior (STPB) and integrated with the Unified Theory of Acceptance and Use of Technology (UTAUT2) model. A total of 1048 valid respondents were purposely gathered to completely assess the behavioral, technological, and sustainable domains of purchasing intentions of hybrid cars through structural equation modeling. From the results, the perceived economic concerns and perceived authority support showed the most significant factor indirectly affecting behavioral intention to purchase hybrid cars, followed by perceived environmental concern. All domains under the theory of planned behavior were significant. However, only performance expectancy, hedonic motivation, and price value were deemed significant on the technological aspect. With the underutilization of hybrid cars in the country, habit, effort expectancy, and facilitating conditions were insignificant. The theoretical framework can be used independently (STPB), or as a whole, for the evaluation of purchasing intention of eco-friendly or smart technologies products. This study was also able to provide implications on the behavioral, managerial, and sustainability aspects of hybrid cars. Lastly, the theoretical implications suggested that the sustainability theory of planned behavior may be extended or applied in holistically assessing different product evaluation, industries, and related studies—even in different countries.