Electric vehicle owners could save on cash after Octopus Energy offered motorists free charging in a revolutionary new scheme. Car owners who resell the power from their vehicle batteries back to the grid during peak hours will be able to benefit from the scheme and could save as much as £850 a year in charging costs. Octopus Energy hopes that the scheme will help motorists save money compared to charging on a standard variable tariff. The guaranteed free charging is part of a new mass market vehicle-to-grid tariff (V2G) launched by the energy group. Although the tariff is still in its early d…