  Quantitative understanding of the best possible performance of nanomotors
allowed by physical laws pertains to study of nanomotors from biology as well
as nanotechnology. Biological nanomotor F1-ATPase is the best available model
system as it is the only nanomotor known for extreme energy conversion near the
limit of energy conservation. Using a unified theoretical framework centred on
a concept called directional fidelity, we analyze recent experiments in which
F1-motor's performance was measured for controlled chemical potentials, and
expose from the experiments quantitative evidence for the motor's multiple
extreme performance in directional fidelity, speed and catalytic capability
close to physical limits. Specifically, the motor nearly exhausts available
energy from the fuel to retain the highest possible directional fidelity for
arbitrary load, encompassing the motor's extreme energy conversion and beyond.
The theory-experiment comparison implies a tight chemomechanical coupling up to
stalemate as futile steps occur but unlikely involve fuel consumption. The
F1-motor data also helps clarify relation between directional fidelity and
experimentally measured stepping ratio.
