It’s safe to say that “Guardians of the Galaxy: Volume 3” is an emotional roller-coaster, a fan-friendly ride through “the feels” that puts our motley, space-traveling crew in peril and revisits old trauma as it does.

If you’re the least bit attached to these characters, you can’t helped but be moved. A little.

But at some point, as we revisit “Volume 3’s” major subtext — grimly cruel animal testing — for the umpteenth time, the viewer is forced to realize that a roller coaster is just a piece of engineering designed to deliver frights and breathless simulations of near-death-experience dangers for our entertainment.

At some point, these suffering, doomed and dewey-eyed digital critters are just ham-fisted manipulations that aren’t so much moving as triggering. All that’s missing is Sarah McLachlan singing underneath pictures of neglected and abused puppies, the only “on-the-nose” song missing from the usual “Original Hits, Original Stars” soundtrack.

The laughs are fewer and farther between as writer-director James Gunn bids this career-making franchise farewell and tries to transport his jokes-that-take-no-prisoners tone over to Warner Bros. and the DC comic universe. And he’s decided to leave Marvel with a Rocket — the violent, wise-ass and tech-savvy raccoon who doesn’t think he’s a “raccoon” — origin story.

No, that was never going to be pretty.

Star Lord Peter (Chris Pratt) has crawled into a bottle since his ex-assasin love Gamora (Zoe Saldana, Best in Class, Best in Cast) died and came back all cynical and all business with no memory of ever being in love with the dorky human whose taste in music is locked in the early ’80s.

Hurled into a new fight against a new caped, gilded superfoe (Will Poulter) to save Knowhere, the rustic spaceport and Guardians HQ, Rocket gets badly hurt. Nebula and Mantis (Karen Gillen and Pom Klementieff), Peter and the crew realize for the first time how “engineered” he is, and that Rocket can’t be saved without getting around some intellectual property-protecting bomb that was implanted in his gut.

Drax (Dave Bautista), re-grown Groot (the voice of Vin Diesel), a seriously-upset Peter and the Guardians get Gamora’s help with her space-faring criminal pals known as Ravagers (Sly Stallone plays their leader) so that they can infiltrate the headquarters of the corporation that made Rocket the way he is.

An icky “bio engineered” portal that looks like the offal that’s ground into hotdogs must be penetrated, a custom-designed planet called “Counter Earth,” filled with beasts bred and manipulated into wild-boar people, goat folk and the like must be visited and one of the most interesting and menacing Marvel villains this side of Magneto, The High Evolutionary (Chukwudi Iwuji of TV’s “Peacemaker,” “The Split” and “Designated Survivor) must be bested to secure the means of saving “my best friend,” Peter insists.

“Second best,” Drax always corrects him.

Just make sure you don’t fall into a trap, kids.

“It’s not a trap. It’s a STAND off!”

There’s one truly dazzling fight among the many shoot-outs/punch-outs/space battles of this quest, an “Old Boy” inspired blast through a corridor packed with minions, soldiers and foes and lots of slo-mo flips, shots, punches and martial arts and wrestling moves.

The always-amusing fanboy fave Nathan Fillion plays a meat-suited guard amongst the bad guys, a rare light touch added to the generally glum proceedings.

Gunn’s story is making some sort of point about reaching for “utopia” in all the inhumane and cruelly wasteful scientific ways, about human failings and foibles that can’t be engineered away any more than trauma, lost love or simple regret can.

That’s a vague, fumbling over-reach in an action comedy that is never more than five minutes away from a fresh blast of classic rock — whose boundaries are stretched to include RadioHead, The Beastie Boys, The Mowglis and The Flaming Lips here — and never more than 10 minutes away from its next grim, seriously bummer baby Rocket flashback.

We all have our own parameters for how and when we’re willing to be manipulated by a film, and diehard fans of this goofy, jokey trilogy may have more tolerance for this than me. I found the yanking of the heartstrings glib and the attempts at cheap sentiment just that — cheap.

These pictures have grown less cute, less charming and less fun with each passing installment, and this one just drags as it meanders towards its over-hyped lump-in-throat finale.

But you have to respect players who deliver performances that register underneath the makeup, prosthetics and effects, with Klementief, Iwugi and Fillion standing out.

And Saldana’s auditioning for better roles by transforming Gamora into someone we haven’t seen in the earlier films, someone not the least bit invested in playing the “spitfire,” ready for a “meet cute” with a lead character/leading man whose appeal she forgot and, after three movies, we can excused for forgetting as well.

Rating: PG-13 for intense sequences of violence and action, strong language, suggestive/drug references and thematic elements

Cast: Chris Pratt, Zoe Saldana, Karen Gillen, Pom Klementieff, Dave Bautista, Will Poulter, Sylvester Stallone and Chukwudi Iwuji, with the voices of Bradley Cooper, Maria Bakalova and Vin Diesel.

Credits: Scripted and directed by James Gunn, based on the Dan Abnett and Andy Lanning Marvel comic. A Marvel Studios release.

Running time: 2:30