A widespread diffusion of Electric Vehicles plugged into distribution networks is strongly dependent on the establishment of a suitable co-ordinated management of all active resources in the grid. Vehicle-to-grid technology, allowing bidirectional power flows of on-board batteries, would enable a responsive behaviour of vehicles. EVs aggregators, such as swapping stations and car parking, could provide strategic ancillary services for the grid support. Provided an efficient remuneration scheme is applied, EVs could meet responsively the requirements of the grid, activating their participation also in voltage regulation. In fact, electronic equipments of recharge infrastructures would enable to exchange reactive power with the grid without practically affecting the downstream flow of batteries. Reactive power management could increase the opportunities for EVs and the benefit for the network.