"He can’t afford a specially adapted automobile." J K Rowling nonsense!
As an amputee of 15 years (perhaps a Person of Leg), I can drive any automatic. If it was my right leg that was missing, it would be a bit more awkward, having to use my left leg for the accelerator and brake, but I would have soon got used to it.
But a left-leg amputee has NO bother driving an auto!
// to arrive at Robin's wedding ceremony at the end of the novel.//
I have sen that already in a tv episode, but it was not the last episode in the series.