In recent years, automakers have been developing various types of environmentally friendly vehicles such as hybrid (HV), plug-in hybrid (PHV), electric (EV), and fuel cell (FCV) vehicles to help reduce greenhouse gas (GHG) emissions. However, there are few commercial solar vehicles on the market. One of the reasons why automakers have not focused attention on this area is because the benefits of installing solar modules on vehicles under real conditions are unclear. There are two difficulties in measuring the benefits of installing solar modules on vehicles: (1) vehicles travel under various conditions of sunlight exposure and (2) sunlight exposure conditions differ in each region. To address these problems, an analysis was performed based on an internet survey of 5,000 people and publically available meteorological data from 48 observation stations in Japan. This survey obtained information on vehicle conditions such as parking locations, whether the vehicle was in sunshine or shade, locations of operation, and trip distances. This paper describes the benefits and desirable specifications of solar vehicles from the standpoint of well-to-wheel GHG emissions reduction. This study assumed that solar modules would be installed on HVs equipped with extra battery capacity for solar power storage. To summarize the results, total well-to-wheel GHG emissions were reduced by 30% when 1,000 W solar modules and a 4 kWh battery were installed on all vehicles, compared to a reference case with neither solar modules nor a battery. In addition, good results can be obtained by installing a battery with a usable capacity of approximately 4 kWh and a solar panel system with a rated output of 1,000 W, e.g. life cycle GHG emissions can be reduced by 12% compared to a HV.