Battery Electric Vehicles (BEVs) are generally considered a promising solution for reducing greenhouse-gas emissions. Despite increasing sales, techno-economic barriers still hinder their widespread adoption. Market stakeholders are faced with a dilemma to address these barriers, especially in terms of choices that have to be made about car battery capacity and recharging infrastructure investments. While previously considered separately, these choices are not independent and influence car price, recharging speed, and ecological impact. This paper explores various combinations of battery capacity sizes and charging power to define and compare these options. We simulate the needs of 12 scenarios of identical privately-purchased BEVs, by increasing their battery capacity, analyse the owner's and charging operator's cost models before exploring Pareto fronts to conclude with optimal combinations of battery size and charging power, taking into account French urban and rural needs separately. For urban (rural) areas, purchasing a 35-50-kWh (50-kWh) BEV and deploying 22-and 50-kW chargers (50-kW) proves cost-efficient solutions. Policy implications are discussed, and we recommend to revise charging tariffs and pricing methods.