Compare this with the prior episode of unintended accelaration of Audi 5000 cars in 1982-83. This report from the Center for Auto Safety indicates that the suspicion was that the problem was mechanical.
The bars over the sets in parts c, d and e mean complement. The complement of a set is everything that is not in the set. So, for example, the complement of A is all the real numbers that are less than -3 or greater than 0.