Energy conservation strategies for electric vehicles on hills

Because the charge/discharge process of a battery is not perfectly efficient, there is an optimal point before the end of a downward slope at which a battery-based electric vehicle can save energy by engaging neutral (i.e., coasting). As an exercise in classical mechanics involving air and rolling resistance, we find an analytical expression for this distance on constant slopes, together with an expression for the energy saved. We compare the analytical solution to the numerical solutions for constant and sinusoidal hills. However, considering the characteristics of current electrical vehicles, the energy saved is only a few Wh per typical slope, resulting in negligible gains on any realistic trip.