Efficient electric machine

An electric machine having a stator and a rotor which is mounted so as to be rotatable about a rotor axis and has a rotor body, in which at least two permanent magnets are arranged in receptacles, a first of which component magnets is associated with a first set of permanent magnets, and a second of which component magnets is associated with a second set of permanent magnets. The permanent magnets of the first set differ from the permanent magnets of the second set with respect to the material composition, In particular to the magnetic properties, and wherein at least one permanent magnet of the first or second set or at least one composite body has a contour, the cross-sectional face of which, being located perpendicularly with respect to the longitudinal axis, decreases within the respective receptacle towards that end thereof which is radially further to the outside.