Why did he want his old Nissan sedan back so badly?

That’s the question that “The Rover” needs to answer, but never does.

In director David Michod’s grim version of a not-to-distant future in Australia, 10 years after “the collapse,” Eric (Guy Pierce) goes on a bloody car chase after a team of thugs who trade their Jeep in for his sedan.

Without asking.

Accompanied by Rey (Robert Pattinson), the wounded brother of one of the thugs, Eric sets out to reclaim what is his.

But why?

The Jeep is a superior vehicle for the post-society hellscape that Michod paints. There is no explanation of any sort of attachment Eric has to the car. Nothing he or Rey says sheds any light on why Eric is treating the car like it’s the only cure for a terminal illness, to be regained at any cost.

Sure, life sucks in Australia with no laws and no money and no food and all, but why the Nissan? Or Toyota, or BMW, or whatever it is? (It’s so dusty it’s hard to tell.)

One of the characters they meet along the way, a woman who runs a brothel/drug den, even says it out loud as Eric’s threatening to kill her unless she gives him information on the whereabouts of his automobile:

“What a thing to get worked up about in this day and age.”

The film’s attempted answer gives away the ending, so it's not included here, in case you see the film, which isn’t all bad, with some seriously great suspense, a nice moody soundtrack, and a fairly chilling, if not all that creative, look at a post-economy world. (One in which China apparently still plays a role, if the heavily armed fuel train that passes through, painted with big Chinese letters, means anything. The U.S. apparently also still has some standing, as the only money folks will take for gas and bullets is U.S. dollars).

“Twilight” heartthrob Pattinson’s performance against type is even pretty good. He plays a young, beaten down man that Eric describes as a “half-wit,” with strange verbal and body tics. And Pearce’s human ball of rage and amorality is also impressive and genuinely scary.

But why did he want his clunky Nissan sedan back so badly?