This paper describes the design and manufacture of a highly practical electric medium duty bus called the WEB for Suntory (WEB: Waseda electric bus). The new electric medium duty bus has a 55-passenger capacity, which is significantly greater than the other vehicles in the WEB series. This project prioritized weight reduction and maximization of the passenger compartment space to develop a bus that meets the requirements for short distance transportation and very frequent charging. A new compact powertrain system incorporating the minimum number of lithium-ion batteries was developed. The intended purpose of the bus is to convey passengers on a plant tour along a steep and low-velocity route located at the foot of a mountainous region. The merits of an electric bus make it particularly suited to this usage scenario and route, which require environmentally sustainable transportation. The dynamic performance and environmental sustainability of the bus were evaluated based on long-term actual driving data. The results found that adopting this bus on this route greatly reduced energy consumption and CO2 emissions due to its efficient dynamic performance and energy regeneration system. The bus was charged from the solar power generation system installed at the plant, thereby further reducing CO2 emissions and running costs.