Not so much an authoritative study as an avid fan’s mash-up, “American Grindhouse” is a sprawling but amusing CliffsNotes-like history of various disreputable subgenres — everything from nudie cuties to sci-fi cheapies, blaxploitation melodramas to blood-soaked splatter pics — that define exploitation cinema. Documaker Elijah Drenner neatly balances wink-wink irony with enthusiastic affection while employing an extensive array of film clips to illustrate the sometimes serious, sometimes snarky commentary by film historians, veteran actors and moviemakers who have produced and/or enjoyed exploitation fare. Aimed squarely at aficionados of celluloid schlock, docu likely will reach its target aud through homevid and VOD.

Drenner and co-scripter Calum Waddell structure “American Grindhouse” as a series of interlocking (and often overlapping) chapters, each devoted to a specific era or genre. Definitions are vague and lines of demarcation are smudgy — there’s even some debate over what a true “grindhouse” really is, or was — but the lack of precision seems altogether appropriate for a pic about such unabashedly slapdash product.

The filmmakers dutifully note, and narrator Robert Forster helpfully announces, that exploitation pics date back to the silent era, and that “Traffic in Souls,” a 1913 white slavery drama from Universal, was the first bonafide exploitationer released by a major studio. By instituting restraints on language, imagery and subject matter in the 1930s, Hollywood inadvertently encouraged a shadow industry of sensationalistic showmen — brassy independents who, unfettered by the Production Code, offered low-budget, high-concept pics ranging from nudist-colony “instructional films” to ultra-graphic gore fests to softcore sexploitation (and, ultimately, hardcore porn).

“American Grindhouse” identifies the golden age of exploitation cinema as the 1960s and ’70s, the heyday of unruly bikers, drug-addled hippies, unregenerate Nazis, African-American avengers, chainsaw-wielding pyschos and scantily clad female convicts at theaters and drive-ins everywhere. The filmmakers stretch their definition of “exploitation” to include some unlikely suspects — beach-party romps such as “How to Stuff a Wild Bikini,” camp classics such as “Night of the Lepus” — but make room for fascinating interviews with directors Jack Hill (“The Big Bird Cage”), Don Edmonds (“Ilsa: She-Wolf of the SS”), Jonathan Kaplan (“Truck Turner”), Larry Cohen (“Black Caesar”) and other B- and Z-movie vets of the era.

The filmmakers rarely attempt to defend even the most unsavory items in their oeuvres. But it’s worth noting that no one — not even Herschell Gordon Lewis (“Blood Feast,” “2,000 Maniacs”) — feels any great need to apologize, either. (Edmonds admits to having a few qualms prior to filming “Ilsa,” but evidently got over them once shooting began.) Nor do the docu’s “expert witnesses” — a lineup that includes helmers John Landis and Joe Dante — express anything but appreciation for the zesty excess of the schlockmeisters. Indeed, Landis goes so far as to suggest Mel Gibson’s “The Passion of the Christ” is no better, and maybe worse, than any exploitation film he’s ever seen.

Ironically, “American Grindhouse” boasts far slicker production values than most of the exploitation pics it excerpts.

American Grindhouse

  • Production: A Gravitas Ventures release of a Lux Digital Pictures production. Produced by Elijah Drenner. Executive producer, Jeff Broadstreet, Ingo Jucht. Directed by Elijah Drenner. Written by Drenner, Calum Waddell.
  • Crew: Camera (color/B&W, HD), Dan Greene; editors, Drenner, Greene, Andrew Goldenberg; music, Jason Brandt; sound, Garrad Whatley. Reviewed at SXSW Film Festival (Spotlight Premieres), March 16, 2010. Running time: 81 MIN.
  • With: Narrator: Robert Forster.
  • Music By: