The Autobots are large, lumbering outer space robots that turn into Camaros and Hummers, but they’re gracious. Harming humans is against their credo. They’re apologetic after stomping on terracotta pots in the yard. Best yet, they’re the ultimate wingmen. Not every nebbish teen is told humankind’s fate rests in his hands while standing aside a tube-topped teen hottie out of his league.

Such savory fantasies writ large are a specialty of Transformers, and they strike a perfect tone for source material more than 20 years old. The movie is based on a line of Hasbro toys and a concurrently successful cartoon. If it’s evolved, it’s been with arrested development. After all, can’t the simple pleasures of speeding cars shifting into gigantic robots and back again still be cool?

The good guy Autobots and bad guy Decepticons shown here are, for the most part. It’s a shotgun wedding of director Michael Bay’s master-of-disaster destruction to executive producer Steven Spielberg’s otherworldly wonderment seen in past endeavors from his Amblin company.

Call this a Ka-Blamblin production, with many jaw-dropping widescreen marvels: Decepticons busting buses, evil jet Starscream’s bombing strafes, Optimus Prime’s fluid, heroic movements.

Stuff blows up bigger than any other movie this summer, but not always better. Action in a Black Hawk Downtown climax — a clash of cars, semis, helicopters, jets and tanks — becomes just another disorienting digital blur of sparkplugs and pistons to which the mind waves a white flag. Still, if this vehicle ultimately runs on fumes, it’s only because the gas was revved so hard.

Both breeds of Transformers are without a home planet once Decepticon leader Megatron takes over and ensures its obliteration. Each is chasing the Allspark, a power source that, in Decepticon hands, could make mean all electronic equipment on Earth and assure them galactic domination.

An unlikely central figure in this war is Sam Witwicky (Shia LaBeouf), who’s hawking his ancestor’s memorabilia on eBay to finance his flow-chart dream of cool car, hot girlfriend, shed geekdom. His beat-up Camaro, though, really is Bumblebee, a soldier in the small army of Autobot leader Optimus Prime (voiced, as in the cartoon, with the old-oak-tree tones of Peter Cullen).

These benevolent ’bots tell Sam they need his trinkets to find the Allspark, so it’s only fair they provide an awfully adventurous first date for him and tiny miniskirt-wearing Mikaela (Megan Fox).

This Earth-saving mission against the in-pursuit Decepticons takes on the usual motley crew of military men (Josh Duhamel, Tyrese Gibson, Jon Voight, John Turturro), computer hackers (Anthony Anderson, Rachael Taylor) and hapless parents (Julie White and Kevin Dunn).

Shrill laughs are a staple for Bay, and there’s plenty of loud, shouting gags that work. But White and Dunn draw huge laughs in an uncharacteristically light scene for the Bad Boys director.

It’s subtle visual slapstick as the Autobots cram into suburban spaces to avoid detection at Sam’s house, even if it would make more sense for them to shift to cars and park on the street. After all, pretense to logic is pretty much forfeited when giant robots from outer space are main characters.

Thankfully, LaBeouf balances out against the heavy metal to cement his rising-star hype. Sam’s wit’s as quick as legs that do distance sprints with an exasperated what-now hustle. Poor guy even has to fight off, in his boxers, one pesky little Decepticon that’s part Johnny Five, part Gremlin.

Such a mix of reverence and winking ridiculousness is hard to pull off, but Transformers does it. It’s easily Bay’s best pure thrill machine since Armageddon, and its apocalyptic battles more than live up to the what-if clashes kids brewed up at home with action figures way back when.