A husband-and-wife directing double act has graduated from music videos to feature films with one of the sunniest comedies of the year, writes Donald Clarke.

JONATHAN Dayton and Valerie Faris, directors of the charming American road movie Little Miss Sunshine, have involved their family in a complex global adventure. Lurking in the foyer of the Edinburgh Sheraton, I observe the couple, united both personally and professionally, laying various recreational options before their children. Dinner must also be organised. Transport to the next great European city has to be discussed.

Dayton (49 years old, straw hat, personable manner) and Faris (a year younger, artfully disordered hair, equally Californian) must, in such stressful circumstances, feel some strain on their relationship.

"Well, there are times when it is a little claustrophobic on this tour," Dayton says. "But much of our energy is focused not at one another but outside into the work. But we both love the work so much we enjoy sharing it together."

"Yes that's right," his wife agrees. "If we focused that much attention actually on one another it would be hard. Very hard."

Dayton pauses to take mock (I think) offence: "Oh really? How hard exactly?"

The Dayton Faris Travelling Circus cannot help but remind one of the escapade at the heart of Little Miss Sunshine. The picture follows a gloriously dysfunctional family - the uncle is a suicidal Proust scholar; the dad is a failed motivational speaker; the teenage son refuses to speak - as the clan's youngest daughter is transported to a children's beauty pageant. This unlikely bunch make their way from New Mexico to California in a rickety old van that works only slightly more often than it doesn't.

The key metaphor is unavoidable: the vehicle, like the family, may have its functional inadequacies, but it will eventually get its passengers where they want to go.

"That is interesting," Dayton says. "We certainly saw the importance of the bus early on as a metaphor. But the true impact didn't really reveal itself until we saw the first cut. We originally didn't end the film with the van, but it quickly became clear that the van was a character and we needed it in the last scene."

"It was important that we had the broken horn honking," Faris, who often finishes her husband's sentences, continues. "This was a reminder that everything is not fixed back together perfectly. Things are still sloppy. They still have their problems. They may not ever be the best of friends but they can tolerate one another, and I think we want the film to be about the value of respecting one another and tolerating one another. That is what we believe families are about."

Now this is interesting. Jonathan Dayton and Valerie Faris, an impeccably liberal coalition whose career to this point has been dedicated to making videos for such bands as The Red Hot Chili Peppers and Smashing Pumpkins, have, arguably, delivered a film with quite a conservative message. Little Miss Sunshine seems ultimately to suggest that proper consolation and firm support can only be found within the bosom of the family. This is a moral that would appeal to George W Bush, would it not?

"I don't know what it is like in Ireland, but in America the political right feel like they own the notion of family," Dayton says. "And that's not right. Look. Val and I are far to the left of the administration - not that that would be hard. We see the film as being more about the value of the family than family values . . . "

Faris jumps in. "The way the right have commandeered morality and the family is really frustrating and evil. We have here a gay uncle as part of the family. The father is a stepfather of one child and a father of another child of his own. You can create a family in your own definition. I am sick of the nuclear family being the only definition."

Dayton points out that Little Miss Sunshine, after being picked up by Fox Searchlight at the Sundance Film Festival for more than $10 million (€7.8 million), went on to win positive reviews from both liberal and conservative newspapers. And, to be fair, during its occasional satirical moments, the film does direct its fire more at the right than the left. Indeed, one might regard the final act, set at a grotesque juvenile beauty show, as an attack on the more bizarre enthusiasms of Middle America.

Fair enough. No sane person could object to a film baulking at the sexualisation of young children. But what then is this apparently decent family doing there? Surely, in the aftermath of the JonBenét Ramsey case, everybody in America knows how vile these events are.

"There are several issues," Valerie says. "There may be a lot of people who have seen documentaries on the pageants. But I think a lot more people would be shocked to discover what goes on. This family might originally just think of it as a talent show. But their main focus is that their daughter loves it. I remember when our daughter wanted to get into baton twirling I was unsure. I thought it was kind of creepy. But, ultimately, you do want to cultivate ambition."

Enough quibbling. Little Miss Sunshine, whose fine cast includes Toni Collette, Alan Arkin, Steve Carell and magnificent newcomer Abigail Breslin as young Olive, is a cracking little film and marks a successful conclusion to five years of hard graft by Dayton and Faris.

Given the couple's success in the world of music videos, it is, perhaps, surprising that it took them so long to get around to directing a film. They were the folks behind the baroque promos for Smashing Pumpkins' Tonight, Tonight, Oasis's All Around the World and Red Hot Chili Peppers' Californication. After all that visual complication, they have, however, settled on a surprisingly unfussy look for their debut feature. Glancing at the long, long opening dinner party sequence - no frenzied fast cutting here - one could be forgiven for concluding that Dayton and Faris were consciously trying to distance themselves from the flashy techniques of music video.

"Oh, absolutely," Dayton says. "That is not just the back of your mind. It is right at the front of your mind all the time. We were really excited about abandoning all those video techniques. Not that we did much fast-cutting in our videos. But, yes, we really wanted to strip it down."

"We wanted you to not think about the film-making," Faris continues. "We wanted to just get out of the way. That was our goal.When people talk about this film they don't tend to talk about the direction. But. you know. when somebody says something nice about the actors or whatever. that reflects well on all of us."

Faris and Dayton appear to have achieved more with their lives than they could ever have expected when they met as film students. I think of a comment Faris made earlier while talking about her children's ambitions. She described the way all juvenile basketball players move as if they believe they might one day play for the NBA. "Of course they never will," she said.

Maybe. But Dayton and Faris's most extravagant dreams appear to have come true. Here they sit at the Edinburgh Film Festival promoting their first feature film. They count Oasis, Beck and the Chilli Peppers as their buddies. They haven't done badly.

"That's right. This really is such a dream," Dayton says. "Through all that time we had this one fear that, after all the effort, the film might not happen."

Faris overlaps her husband's conversation one more time.

"You don't allow yourself to dream," she says. "We just hoped to make something we could be proud of. We never thought beyond that. We always hoped most of all to make a film we would be happy with."

They seem to have done that.

"Well I suppose there's always something you're not quite happy with. But, yes, close enough."

Little Miss Sunshine opens today