Polymer compositions containing A) at least one compound selected from the group consisting of polycarbonate, polyester and polyester carbonate, B) optionally one or more optionally rubber-modified vinyl (co)polymers, C) at least one compound selected from the group consisting of polyether amides, polyester amides and polyether ester amides, D) at least one Brönstedt-acidic compound selected from the group consisting of organic fruit acids, inorganic acidic phosphorus compounds and compounds of formula IV wherein R9 and R10 independently of one another denote C1- to C9-alkyl, optionally substituted C5- to C6-cycloalkyl, C6- to C10-aryl or C7- to C12-aralkyl, and Y denotes S or CZ1Z2, wherein Z1 and Z2 independently of one another represent H, C1- to C6-alkyl, cyclohexenyl or cyclohexyl, and E) optionally further additives have permanent antistatic behavior and have improved heat distortion resistance, low-temperature strength, processing stability, stress cracking resistance and, in particular, hydrolytic stability.