This paper presents a multi-layer approach to Cooperative Adaptive Cruise Control (CACC) to improve the platoon cohesion subject to limited vehicle actuation capabilities. The objective of the design is to guarantee that the vehicles in the platoon keep their desired relative position, while maintaining desirable platoon properties in terms of disturbance attenuation. To this end, a multi-layered control architecture is proposed. On the lower layer, a unidirectional CACC is employed, involving information exchange in upstream direction. On the upper layer, a coordination variable is exchanged from each vehicle towards its direct preceding vehicle, thus yielding downstream information exchange. As a result, the leading vehicle is aware of the capabilities of the following vehicles, and therefore, is able to adapt its motion, if needed. Consequently, cohesion of a heterogeneous platoon is guaranteed, even in the case of physical limitations, like engine power limits. The developed technique is verified through simulations and experiments.