One of the great advantages of Full Throttle's intentional disassembly of the heavy machinery of action movies is that the stars stand out more. Cameron Diaz, who's capable of sunburst projection when she's doing nothing but having fun, is not quite like any previous top-billed actress: an adult tomboy star. Katharine Hepburn was independent, wore trousers, and was a manifestly athletic woman, but she came across as more responsible than Diaz, who is a woman but not exactly a grown-up. She makes star acting seem like a form of recreation rather than art or work, which is not something you could say of Hepburn. Diaz has something of a cheerleader's spark (without the coy confectionary sweetness), but an appealing gawkiness that the character doesn't even seem fully aware of (that's the point of the Soul Train sequence in the first movie). She certainly doesn't let it hold her back. Diaz is a total guy's-chick--tough but wide-eyed, both giggly and foul-mouthed, spirited, leggy, unselfconscious. Apart from Danny Boyle's way underrated A Life Less Ordinary (1997) she hasn't had very good material, but she's always infectious, a breathless one-woman amateur spectator sport.

Drew Barrymore is an even more unusual star. Her well-publicized troubles give her acting an emotional undertow, though you scarcely think of her as an actress at all. With Judy Garland and Betty Hutton you could also sense their personal disturbances, but those women were troupers who knew how to keep a lid on it for the good of the show: Garland played her desperation with quiet urgentness, while Hutton went explosive. Barrymore, having grown up with her confusions well-aired, has made a character out of being confused. She doesn't have the focused laserlight of a star, but in The Wedding Singer (1998), Home Fries (1998), Never Been Kissed (1999), and Confessions of a Dangerous Mind (2002) she has displayed a core of traits--eager warmth with fuzzy edges, head-spinning doubts and changes of heart--that Full Throttle uses in its only attempt at coherent storytelling. (Barrymore's history of falling for the wrong guy is behind what the movie calls a plot.)

Barrymore has the sweet-dolorous quality of a Madonna, but one who's entered the game of love and keeps getting tripped up by her most endearing qualities. Diaz comes across as a girl who can take of herself, whereas Barrymore elicits a protective reaction in the audience. She's been in movies over 20 years but, unlike Garland and Hutton, has never formed the veteran showman's armor of expertise. She has the bone structure and coloring to be Julianne Moore's diffident little sister, but not the technique (her enunciation in particular can get mushy) and maybe that's why she's involving in a way Moore never has been. Barrymore isn't consciously presenting herself to us; she's utterly open to the camera.