Too bad Robert Rodriguez and Quentin Tarantino didn’t make their “Previews of Coming Attractions” — Rodriguez’s Machete and Rob Zombie’s Werewolf Women of the SS — into their “Feature Presentations” in this “parody” of a ’70s Z-movie twin bill. Both get more laughs than either Rodriguez’s Planet Terror or Tarantino’s Death Proof. Terror draws more on Dawn of the Dead and Toxic Avenger than on anything by William Castle, with flesh-eating zombies spawned by chemical weapons terrorizing a Texas town. It consists mostly of exploding heads, bodies splattered by vehicles, and Rose McGowan with an M-16 for a prosthetic leg. Unexpected flashes of wit and black humor kept my interest. As for Tarantino, he’s aging badly: he has a role in both films and looks like a cross between Dan Aykroyd and Bob Hope on a bender. Neither do his trademark affectations, trivia, and fetishism (must a woman’s foot hog the foreground of every scene?) still charm, though a car chase and the come-uppance of a psycho (a lovable Kurt Russell) end the tedium on a high.