The optimum design range for an EV would maximize market potential. It depends an the relationship between the cost of extra range and its value to the potential vehicle buyer. This relationship was quantitatively investigated using two existing computer models: a standard EV weight, performance and cost model, and a market model based on a survey of 193 prospective second-car purchasers conducted in 1977. The optimum design range is near 60 miles -for a mass-produced 4-passenger electric car with currently-available lead-acid batteries. With nickel-iron and nickel-zinc batteries, it is near 80 miles. Vehicle or battery changes which add cost, such as air conditioning or higher acceleration capability, tend to reduce optimum range. Doubled gasoline prices would have little effect on optimum range.