Each turbine weighs 110 pounds, + 400 pound battery pack. So 620 total, producing 780bhp and 1170 torque. That is it though. No radiator or any of the other added weights necessary on a typical engine, plus weight savings in the transmission make it quite acceptable, especially given the fuel economy. Diesel is heavier than petrol, but not that much. All super cars have large fuel tanks, so that point is completely mute.