Patent ID: 8738207

Claim:
A hybrid vehicle having a first axle and a second axle and comprising: an engine having at least one working chamber operable for expanding a working fluid; an electric transmission that includes a differential gear set having a first member, a second member, and a third member; a first final drive; and a first electric machine; wherein the engine is connected for common rotation with the first member, the first electric machine is connected for common rotation with the second member, and the third member is operatively connectable with the first axle through the first final drive; an electric drive module that includes a second electric machine operatively connectable to the second axle through a second final drive; wherein the differential gear set and the first final drive are configured to establish a single fixed torque ratio of torque of the first axle over torque of the engine; wherein the single fixed torque ratio is that at which said at least one working chamber operates without throttling, without torque from the engine exceeding a torque necessary to propel the vehicle at a steady vehicle speed, and with the second electric machine freewheeling.