Maximum Torque = Maximum Efficiency?

Simple answer NO

keep in mind there is Max power ,Max torque , Best efficiency.
Each motor is different ,each tune is different but best rule of thumb 1/3 about max torque and below max power.
Shadow

With a typical diesel engine, the answer is generally yes - and many vehicles (the OKA is a superb example, the Nissan TD 4.2 litre is another) are geared such that keeping engine revs around the higher part of the torque curve results in optimum economy.

But this is only a generalisation. There are quite a few diesel vehicles around now that are very highly geared and where peak torque may be above realistic road speeds in top gear.

The query is interesting - but is more relevent to fixed engine-speed applications such as generators, power take offs etc.
Collyn Rivers

If maximum volumetric efficiency translates to the most energy derived from a given amount of fuel, and that point equates to maximum torque output at a given engine speed, then surely that follows?