Yeah, I'd like to see it. OK to take a 13-year old to?
Hmmm... I guess it probably depends on the child's own maturity level and what he's seen so far. I saw Nightmare on Elm Street and The Road Warrior in the fourth grade, when I was nine. By the time I was 13, my parents basically had basically thrown in the towel and were letting me rent anything that I wanted, so I'd seen it all and rented every violent, depraved 70s exploitation flick out there (explains a lot, I know).
The plot is basically that Furiosa (Charlize Theron) tries to rescue the warlord Immortan Joe's sex slaves/breeders and then he chases her down with his army of crazies. Mad Max happens to be caught up in the chase and reluctantly helps Furiosa (shocker!). So, out of the gate, the premise is a sex-slave rescue. After that, the whole movie's basically one long chase scene filled with countless car crashes and horrible deaths. Many, many people get beaten, stabbed, mangled, burned, shot with arrows and guns, run over, blown up and other things I'm sure I'm forgetting. It's bloody and it's recurring. As for sex/sexual violence, there's nothing as graphic as the rape scene in the original Road Warrior, but a pregnant woman does get run over in one scene and someone later cuts her baby out of her stomach to see if it's still alive. We also see some shirtless fat women with their boobs hooked up to milking machines early on, before the chase gets started. At one point, there's a nipply "wet t-shirt" moment with Immortan Joe's "wives." Last, late in the movie, there's a scene with a naked woman chained up on an old powerline tower as bait, but you can't really see much except her butt.