Could we have a feature to allow a group of fields to be extracted from a class or structure into a sub-class or -structure? So we could turn:
class Car
{
  string make;
  string model
  // Fields relating to the engine
  FuelType fuelType;
  int capacity;
  int horsePower;
};
into:
class Engine
{
  FuelType fuelType;
  int capacity;
  int horsePower;
};
class Car
{
  string make;
  string model
  // Fields relating to the engine
  Engine engine;
};