Paul-you would be int. in these cuttings. Certainly seems, as per your investigations into the green engine that elec.cars are not the panacea we thought they would be.
The flywheel concept you spoke of ( mechanical battery) sounds similar to what the old Lanz Bulldog tractors used 50 + yrs ago with ,I think , one big cylinder which drove two huge and heavy flywheels. They made a distinctive sound as the ignition in the cylinder seemed to only go off every few seconds! Once up to speed, the pulling power was all the energy stored in the high speed flywheels.
Cheers
TED C