Andrea Arnold might have been making a career out of Academy ratio, but there's nothing routine or lazy about how it's employed in American Honey, a cross-country road trip saga that loves the inside of a van just as much as the open road it drives upon. Outside is a succession of coming-of-age scenes, sweet ones, funny ones, traumas, excitements, romances, violences of all sizes, none so monumental as to constitute a plot point; plot is only a verb, after all, used when drawing maps. Inside the van is a complement to that story, yet singular. Restricted by space, the camera stops roving so hungrily. Nothing too dramatic can happen to the characters, either. They are boxed in, about 14 young people, give or take, stuck gazing out of Academy ratio-sized windows, sharing sing-alongs, getting high with dog.

The film loves its protagonist, Star, most of all, the tight framing keeping her in intimate proximity most of the time. She's the newest member of a 'mag crew', going door-to-door, truckstop-to-motel selling magazine subscriptions in what is almost certainly a pyramid scheme. Star is at once the perfect mark — lonely, impoverished, abused — and the most heroically inept employee Riley Keough's manipulative, Confederate flag-wearing boss ever tried to exploit. She is incapable of lying in order to make a sale, or perhaps at all. She is impulsive, somewhat easily led on (particularly by Shia LaBeouf's punkish middle-manager Jake, who recruits her into the group with his cocky charm), still vulnerable enough that I felt constantly worried for her safety; but she's also self-possessed, compassionate in a 360-degree arc, constantly standing up for herself and others.

Her unfailing honesty is ingrained in the filmmaking; more than ever this is a documentary of its own making. It really is a bunch of young people driving across America in a van. Some of them, I get the impression, are playing themselves, or near enough. The director keeps an almost reverent distance from their stories, never forcing this supporting cast to reveal themselves through dialogue. I can only hope they were comfortable with everything else on display.

For such an expansive, almost three hour-long odyssey, there are some merciless edits of space and time. Conversations are cut off in mid-flow; songs end before they get to the good part; moments of conflict go unresolved as we are whisked off to the next time and place, as if the film has been re-edited by an impatient teenager with his finger on the iPod click wheel (an appropriately dated reference for a film set in the present yet following door-to-door magazine salespeople). The question American Honey keeps asking, and maybe you will too, is not 'where are we going?' but 'how did we get here?'

One might decry the obviousness of the frequent natural world inserts — ants crawling over discarded chips, a bird overhead, wasps everywhere — but like everything in American Honey, they are obvious because they are true. They needn't be read as metaphor, mined for some other significance outside their purview. 'Real' life is exactly as on-the-nose as flirting to the tune of Rihanna's 'We Found Love', because it's a popular song that people like flirting to. Nature is on camera mostly because it was there, and Andrea Arnold wanted to acknowledge it. When a film so guilelessly rejects thematic consistency, allegory and metaphor, it's easy to forget how artfully and gracefully chosen each moment and every observation, every close-up and cut and ambient noise, is. The film is not 'going anywhere', not proceeding towards a unifying conceit, a message of grand social importance. Instead, it keeps looking back to the time that it was shot, an evocation of fleeting moments that had already fled before they even happened. These kids are selling magazines, for crying out loud; time has already left them so far behind. It's out there, somewhere, beyond the edge of a narrow frame, outside the cramped confines of a dusty white van.