No, a torque converter is actually a torque multiplier as well as acting like a clutch - it's slippage allows higher engine revs at any given road speed according to load. At standstill and max throttle it can double the torque applied to the transmission input shaft. This is why autos can run taller final drives and taller gears and still match the accelleration of a manual. Well, mostly. However the heat produced and the inherent inefficiency of the oil medium in producing postive drive means there are some losses. Most of the loss or lower power output of the auto cars compared to the manuals is because of the heavier transmission components (higher inertia and higher friction) and also the greater number of "interruptions" to the torque flow ie bands, clutches etc. Every connection in the driveline causes heat and therefore loss of power output. Spot on Geoff, well written.