Somewhere in the middle of Crash, the remarkable new film from David Cronenberg, James Ballard (James Spader) is caught in traffic. The cars on the highway are at a standstill, stymied by an impact farther up the blacktop. Ballard is driving a vintage Lincoln Continental, the kind of convertible JFK rode through Dallas. The car belongs to Ballard’s new friend Vaughan (Elias Koteas, from Exotica), a visionary of sorts who sees car crashes as “fertilizing,” rather than destructive, events. In the car with Ballard and Vaughan is Ballard’s wife, Catherine (Deborah Kara Unger), who is growing more and more attracted to Vaughan — she and Ballard seem to achieve sexual bliss more and more often by comparing notes on their most recent adulteries. You could almost consider this menage a trois a special kind of post-nuclear family.