The adoption of an energy aware driving style, often referred to as ecodriving, is a promising way to save, besides of costs, non-renewable fossil fuels. In a previous paper we presented a two-layer control approach for ecodriving which tracks an optimal speed profile resulting from the first layer under the presence of traffic in the second layer. In this paper, we extend the developed control approach to a convoy of vehicles and determine, whether it leads to safe and stable convoys and whether an increasing number of vehicles within the convoy leads to an increased fuel efficiency. Thereby, we focus on two different prediction methods of the preceding vehicle: in the first case we assume perfect knowledge of the future movement of the preceding vehicle, whereas in the second case we assume the current speed of the preceding vehicle to be constant during the prediction horizon. It is shown that the higher the number of vehicles the more fuel saving from the optimal solution can be recovered.