It's not uncommon for people to wax philosophical while sitting behind the wheel of a car, and the single-shot, semi-improvisatory ''dashboard cam'' monologue has become Abbas Kiarostami's signature trope: It is to the celebrated Iranian director what circuses were to Fellini or the silence of God was to Bergman. Ten, in form, is a variation on Kiarostami's 1998 ''Taste of Cherry,'' only this time the designated driver isn't mired in monosyllabic gloom. She's a beautiful, feisty, divorced single mother in her 30s, wearing a head scarf but also chic sunglasses (think Catherine Zeta-Jones in the land of Islam), who carries on a series of dialogues with her extraordinarily bratty and articulate preteen son, her far less liberated sister, and, in one amazing scene that sounds as if it might have come out of a Tehran edition of ''Taxicab Confessions,'' a prostitute. This isn't the land of hushed, dawdling subservience we're used to from previous Iranian films -- that world of mute children and furtive, often childlike adults. It is, rather, a glimpse into a society that has grown more open, more free, and also more casually selfish in its interpersonal aggression. Mania Akbari, as the unnamed driver, seems to shoulder all of the film's contradictions in her world-weary yet spirited defiance.