The invention is directed to polymer compositions comprising components (a), (b), (c) and (d): (a) 80 to 97% by weight of component (a) comprising a copolymer (a1) of styrene (a11) and methyl methacrylate (a12), wherein the amount present of (a11) is from 70 to 90% by weight and the amount present of (a12) is from 10 to 30% by weight, based in each case on (a1), (b) 3 to 20% by weight of polyphenylene ether as component (b); (c) 0 to 2% by weight of polystyrene as component (c); (d) 0 to 17%, in particular 0 to 15% by weight of conventional additives as component (d), having improved heat resistance, surface hardness, depth of color and gloss.