As part of a bold new crop of Mexican films, Alfonso Cuar–n’s “Y Tu Mamý Tambi*n” (And Your Mother Too) takes the realism of “Amores Perros” into the bedroom. While it certainly attracts attention, the carnal sex of Cuar–n’s film is neither overdone nor ubiquitous, but it still plays a very significant role.

“Y Tu Mamý Tambi*n” uses sex to elicit truth from its characters, who, like typical teenagers, often ignore the world around them and create “personal mythologies,” to use the words of the film’s unnamed omniscient narrator. Cuar–n dances delicately around blatant characterization and storytelling — his characters have secrets, and his plot has hidden history and depth. Their slow revelation through pulsing dialogue and natural acting creates a gorgeous fantasy with just enough reality to make it bittersweet and believable.

Evoking the French New Wave classic “Jules et Jim,” Cuar–n follows his teenage protagonists, Tenoch and Julio, on the wet dream of road trips. They travel on blindingly sunny roads with Luisa, a sexually experienced, free-wheeling older woman. Prompted by a cheating lover and the boys’ delicious, fabricated story about a beach called Heaven’s Mouth, Luisa agrees to the journey and to fulfilling the expected role of the older woman.

But the film is more than a sexual coming-of-age tale. While Tenoch and Julio may be as horny as the next “American Pie” character, they display intelligence — if selectively — regarding the world around them and tenderness towards each other. Most significantly they emote the exuberance of youth through their willingness to create fantasy in spite of their own worries and insecurities.

Sex helps them escape in this sense. Cuar–n’s depiction of teenage sex may seem shocking to American audiences in its explicitness, but it should shock us for another reason: this is teenage sex without stupidity. Instead, it is honest enough to be awkward and euphoric simultaneously.

But perhaps most significantly and most unlike American films, “Y Tu Mamý Tambi*n” uses its sex for a particular purpose that is central to the film. While it does capture the fantasy of youth, sex also reveals hidden friction between characters.

Along with a few tequila shots, sex spurs Tenoch and Julio to physical fighting and adulterous revelations (and your mother too). Its paradoxical union of pleasure and violence perfectly mirrors the tension in the larger plot, between the reckless abandon of taking a road trip and ignoring political protests, armed rebels, and lurking disease.

Although it often interrupts the flow of events and sometimes seems misplaced in a realist film, the omniscient voice-over does clue the audience into truths that the characters and the land keep hidden. The voice-over reveals, for example, that Julio once witnessed his mother commit adultery and that Luisa is rather obsessed with death.

The voice-over also incidentally tells the tale of the scarred landscape where animals were massacred and car accidents took lives. By separating the characters and the scenery from their hidden sorrows, the voice-over prevents the film from being tragic. Both the characters and the audience want the road trip to be a dream, and the voice-over provides an effective cleavage between truth and fantasy.

Cuar–n allows us to indulge in the youthfulness of his characters. Unlike “Amores Perros,” his film keeps grittiness under the taut, tan skin of summer. Cinematographer Emmanuel Lubezki, who previously collaborated with Cuar–n on “A Little Princess” and “Great Expectations,” tones down the stylized camerawork of those films.

Instead, he opts for shots that capture the film’s central tension between dreams and reality. Lubezki switches from sun-kissed roads to washed-out beaches, from golden bedrooms to musty motels.

As may be expected in such a textured film, Cuar–n’s actors give performances that are understated and natural. As Tenoch, son of a somewhat corrupt secretary of state, Diego Luna (“Before Night Falls”) is simultaneously fresh-faced and sexual, keeping appearances like his father.

Gael Garcia Bernal, a veteran of “Amores Perros,” infuses Julio with necessary lightness. Both actors capture the insecurity of teenagers on the verge of adulthood, and their chemistry crackles through fast-paced, sexually charged dialogue.

“Y Tu Mamý Tambi*n” can easily be pigeonholed as a movie about sex. But, in fact, sex is what illuminates the more significant elements of the film. It reveals and forms the relationships between its characters and the strange place they occupy in their lives, between the dream of youth and the truths of adulthood.

Their road trip is a final act of abandon that is nonetheless spotted with sorrows and quiet worries. Through careful storytelling and characterization, Cuar–n creates a slightly imperfect fantasy. His film manages to be real, yet dreamy, evoking a strange, bittersweet nostalgia for carefree yet troubled youth.