Also, isn't the power figure provided (the 225kW) typically at the motor, not at the wheels (e.g. hp vs bhp)? The Tesla drivetrain is likely more efficient than a typical ICE drivetrain, which has a 15% "rule of thumb" loss, but since they are using a differential & half shafts vs in-hub motors, there's still some loss there. Along with the losses you note, it may make the total % loss more reasonable.
(On the other hand, maybe the power rating is under-reported...
Tesla Model S Cranks Out 428 Horses At The Wheels: Video)