Speeding and drunk driving does not automatically make you crash. A common police car following manoeuvre may better explain the directional deviation and crash killing the princess in August, 1997.
Video illustrating the PIT-manoeuvre used by the US Police to destabilize a car:
Further explanations in the (Swedish) post
Knuffen som stoppar bilmarodörer
Knuffen som stoppar bilmarodörer