Except that he never once uses the words “dude” or “stoked,” Vin Diesel is quite believable as an xtreme sports enthusiast in “XXX.”

Synergizing the summer’s biggest trends, xtreme sports and James Bond knockoffs, “XXX” is propelled by the ironic humor and gargantuan biceps of Diesel. He plays a small-time hood recruited by the government, which needs a secret agent to stop a Russian mobster from taking over the world. Anyway, that’s what the feds say they need. But the real reason they want Diesel is to make nihilistic wisecracks, snowboard down mountains, remove his shirt insouciantly and treat Prague like a skateboard park.

If you believe a moment of “XXX,” then you’ve suffered too many motocross-related head injuries, but believability is not the point. “XXX,” like last year’s Diesel vehicle, “The Fast and the Furious,” is built for speed and for fun, and it delivers. Mostly that’s because Diesel, with his voice like a stereo woofer and his Anna Nicole-Smith-esque chest measurement, is such a charismatic action star.

“XXX” is fresher and more entertaining than, say, the last eight Schwarzenegger inaction films. Diesel is visibly willing to do lots of his own stunts, unlike Arnold, and director Rob Cohen’s storytelling is fluid, funny and sharply structured, although he has a sick-making fondness for crooked camera angles.

The Diesel/Cohen revamp of action formulas reaches a crescendo in an amusingly over-the-top moment when Diesel’s Eurotrash love interest (Asia Argento and, like all Eurotrash love interests, she looks like she could use a 72-hour nap) pulls a gun on him. So he grabs her arm in a hug/chokehold, mistakenly leaving her other arm free, so she can pull yet another gun on him.

That’s good popcorn moviemaking, folks, and if “XXX” isn’t completely successful in giving action movies a facelift, it is, nevertheless, an xtremely xciting movie.