Low driving range is one of the main obstacles for a larger market penetration of future autonomous Electric Vehicles (EV). Heating, Ventilation and Air Conditioning (HVAC) system size and consumption can lower the range of an EV from 5 to 50%, depending on the outside weather conditions, vehicle size, vehicle envelope characteristics and driving style. The present paper investigates the impact ... [Show full abstract] of vehicle transparent envelope design and characteristics on vehicle performance, that is EV driving range or HVAC size for internal combustion vehicles, considering traditional glazing solutions as well as switchable glazing technologies. Sensitivity analysis on vehicle transparent envelope properties was carried out by means of a lumped thermal model, tested in pull-down test and static summer conditions. The results show that by optimizing transparent envelope characteristics, the size of the HVAC system can be largely reduced (up to 25%) by maintaining even higher comfortable level inside the vehicle (maximum perceived temperature reduced by 10% and higher surface temperatures reduced by 55%). Air conditioning load reduction can impact the driving range for EV between 5 and 10%, depending on battery capacity and vehicle average consumption. Larger improvement could be achieved by optimizing the opaque part of the vehicle envelope as well. This result is particularly important for material and component manufacturer supplying the automotive industry, and could positively impact on a deeper penetration of EV in the mass market.