In this paper an eco-driving assistance system for reducing the energy consumption in electric vehcles is proposed. An accurate electric vehicle model is developed and an optimal control problem is formulated. The optimal control problem is solved based on dynamic programming. As a result an energy-optimal speed profile is obtained. This speed profile is displayed to the driver for eco-drving assistance. Experiments indicate that the speed profile can be tracked well by the driver and that the energy consumption can be reduced substantially.