The parents of a college student in a Tesla crash say she was killed by flames and smoke as she tried but failed to escape the burning car because of a design flaw making it difficult to open the doors in fires, according to a lawsuit filed Thursday. The new legal threat to Tesla filed in Alameda County Superior Court comes just weeks after federal regulators opened an investigation into complaints by Tesla drivers of stuck-door problem. A fourth was pulled from the car after a rescuer smashed a window and reached in. The lawsuit follows several others that have claimed various safety problems with Tesla cars. In August, a Florida jury decided in favor of the family of another dead college student, this one killed by a runaway Tesla years ago, and was awarded more than $240 million in damages.