“Machete”

Certainly, “Machete” is the best feature-length extension of a fake movie trailer in Hollywood history.

Fans who saw the trailer in Robert Rodriguez and Quentin Tarantino’s 2007 “Grindhouse” double-feature continually asked Rodriguez to turn the make-believe ad featuring Danny Trejo into a real blood-and-guts vengeance flick.

Rodriguez has complied, maintaining a fair amount of the wicked humor and every bit of the savage bloodshed the trailer promised.

Viewers get precisely what they’re paying for: beheadings, skewerings and kill shots to the head by the dozen, with other means of dispatch – death by corkscrew, high heels, crucifixion – tossed in for variety.

They also get a crazy range of supporting players – Robert De Niro, Jessica Alba, Steven Seagal, Don Johnson, Lindsay Lohan – all having a ball committing atrocities.

Rodriguez is like a kid in a candy store – a pretty twisted kid in a very sick and disturbing candy store – but fans of his R-rated stuff, including “From Dusk Till Dawn” and the “El Mariachi” movies, already knew that and are on board.

They’ll most definitely be on board with “Machete,” which gives ex-prison inmate Trejo his first lead role in a long career of mostly smallish parts as taciturn tough guys who choose their words carefully.

Trejo’s Machete doesn’t talk much, either, but he’s a commandingly fun presence, a former Mexican federal cop working as a day laborer in Texas after being left for dead by drug kingpin Torrez (Seagal), who also killed his family.

Trouble follows Machete, who goes on the run after he’s hired as the fall guy in an assassination attempt on a radically conservative anti-immigration state senator (De Niro).

“Machete” has the same made-on-the-cheap, outlandishly violent ’70s vibe as “Grindhouse,” down to the funky music provided by Rodriguez’s band Chingon (besides co-directing with Ethan Maniquis, Rodriguez also is a producer, co-writer and editor on the movie).

To clear his name and take sweet revenge, Machete goes on a rampage that puts him up against Seagal’s Torrez, De Niro’s senator, a slimy political kingmaker (Jeff Fahey), a ruthless border vigilante (Johnson) and scores of lesser thugs.

Allies rally to Machete’s side – a right-minded immigration agent (Alba), a taco vendor who moonlights as a revolutionary (Michelle Rodriguez), and Machete’s priestly brother (Cheech Marin).

Like most of Rodriguez’s movies – whether his family flicks or his action romps – “Machete” is never as fun or funny as he thinks it is.

There are clever wisecracks, and some of the action is fresh and inventive, if you don’t mind blood and body parts flying in all directions.

Yet much of the violence is repetitive – when you’ve seen one head sent tumbling by a machete, do you really need to see 10 more? – while the movie lapses into indolence in between action sequences, the characters uninvolving, the dialogue boring.