Introducing effective technologies to reduce carbon emissions in the transport sector is a critical issue for automotive manufacturers to contribute to sustainable development. Unlike the plug-in electric vehicles (PEVs), whose effectiveness is dependent on the carbon intensity of grid electricity, the solar hybrid vehicle (SHV) can be an alternative electric vehicle because of its off-grid, zero-emission electric technology. Its usability is also advantageous because it does not require manual charging by the users. This study aims at evaluating the economic, environmental, and usability benefits of SHV by comparing it with other types of vehicles including PEVs. By setting cost and energy efficiency on the basis of the assumed technology level in 2030, annual cost and annual CO2 emissions of each vehicle are calculated using the daily mileage pattern obtained from a user survey of 5,000 people in Japan and the daily radiation data for each corresponding user. We develop a linear programming model to determine the optimal vehicle mix for these users that minimizes the total cost or total CO2 emissions. Incorporating carbon cost and usability cost, which represent the inconvenience of frequent charging for users in the model, we also investigate the balanced solutions between economic, environmental, and usability benefits. The results show SHV as one of the most cost-effective vehicles for CO2 reduction after the plug-in hybrid vehicle with small battery for a wide range of users. Sensitivity analysis on the initial settings shows the importance of technological development in achieving the target.