  We analyze the impact of the leading quantum gravity effects on the
properties of black holes with nonzero angular momentum by performing a
suitable renormalization group improvement of the classical Kerr metric within
Quantum Einstein Gravity (QEG). In particular we explore the structure of the
horizons, the ergosphere, and the static limit surfaces as well as the phase
space avilable for the Penrose process. The positivity properties of the
effective vacuum energy momentum tensor are also discussed and the "dressing"
of the black hole's mass and angular momentum are investigated by computing the
corresponding Komar integrals. The pertinent Smarr formula turns out to retain
its classical form. As for their thermodynamical properties, a modified first
law of black hole thermodynamics is found to be satisfied by the improved black
holes (to second order in the angular momentum); the corresponding
Bekenstein-Hawking temperature is not proportional to the surface gravity.
