In the newer version of the Stepford Wives (2004), it shows some of the "turned" wives doing humanly impossible things like placing a hand on a burning stove, spinning at high velocity, or despensing money like an ATM.
But the ending of the movie shows that
the wives were simply being implanted with chips down their spine; when the control room was destroyed, all the wives simply went back to being their normal selves.
Were some of them robots and some not? Were they gutted and filled with machine parts?