  We extend to non-static black holes our benchmarking scheme that allows for
cross-comparison of the efficiencies of asymptotically AdS black holes used as
working substances in heat engines. We use a circular cycle in the p-V plane as
the benchmark cycle. We study Kerr black holes in four spacetime dimensions as
an example. As in the static case, we find an exact formula for the benchmark
efficiency in an ideal-gas-like limit, which may serve as an upper bound for
rotating black hole heat engines in a thermodynamic ensemble with fixed angular
velocity. We use the benchmarking scheme to compare Kerr to static black holes
charged under Maxwell and Born-Infeld sectors.
