Didim lies well south of İzmir, past Söke and the Büyük Menderes delta. The route uses the Aydın motorway for most of the distance and only drops onto ordinary road for the last stretch to the coast.
That motorway share is why the timing barely moves. Across our recorded runs the spread is only ten minutes, which is unusual on a journey this long. Traffic in and around İzmir at the start is the one variable worth allowing for.
Altınkum is the beach end of Didim and where most hotels and apartments sit. Akbük is a quieter bay about twenty minutes further, and the Temple of Apollo at Didyma is a few minutes inland from the centre.
Bodrum Airport is sometimes suggested as an alternative. It is nearer in a straight line but the road is slower, so İzmir usually wins on time.