It has always been said that the car was actually being driven by Infanta doña Beatriz, not doña María Cristina.
Fur, in his recently-published book of memoirs, Count Alessandro Lecquio di Assaba, Beatriz's eldest grandson, says that his grandmother told him Gonzalo was actually driving the car and not her.
Arturo Beéche
According a book I have on Queen Victoria Eugenia "On August 13th, Beatriz (Beatrice) was driving (a) car with her brother Gonzalo. They were going back to the villa that their father had rented out in Portschach, on the edge of Lake Worther, in Carinthia, next to the Italian and Yugoslavian borders.
A sudden move by a drunken cyclist, Richar van Neumann, suddenly made Beatriz turn the wheel, but lost control of the car and hit the outside walls of Krumpendorf Castle, near Klagenfurt.
Apparently, according to a Klagenfurt doctor, neither driver nor copilot sustained any injuries. However, when they got to their villa, the "infante" complained of intestinal pains. They urgently called a doctor, who diagnosed a severe internal haemorrhage".
Ena was sent a telegram to France, and after a terrible journey she amde her way to her dying son, whom they called "the Einstein" of the family. He was buried in the local cemetery awaiting re-buriel elsewhere. After the funeral, the exQueen travelled to London with her daughters while Alfonso went to Rome, an evident sign of their matrimonial fracas.