By DAVID GERMAIN

AP Movie Writer

Rupert Grint's far from the top of the class at Hogwarts wizardry school, where he co-stars as all-around average student and Harry Potter sidekick Ron Weasley in the fantasy franchise.

Driver's education doesn't seem to be Grint's best subject, either.

With "Driving Lessons," Grint becomes the first of the three "Harry Potter" stars to take the lead in his own movie. Grint's a suitably awkward, sullen teen in this tale of a sheltered kid busting loose for the first time, but it's a one-note performance in a fairly pedestrian coming-of-age drama.

First-time director Jeremy Brock, whose screenwriting credits include "Mrs. Brown and "Charlotte Gray," loosely based his script on his own teen experiences as a vicar's son who took a job helping out British actress Peggy Ashcroft.

Grint's Ben stands in as Brock's alter-ego, a shy 17-year-old dominated by his loving but overbearing mother (Laura Linney), a minister's wife who suffocates the family with her do-good Bible-thumping and judgmental demeanor.

Ben takes a job as assistant to Evie (Julie Walters, who plays Ron Weasley's mother in the "Harry Potter" flicks), an aging, eccentric actress who's coarse, boozy and shameless, the absolute opposite of our hero's puritanical mom.

Unable to drive herself, Evie winds up dragging Ben along as her chauffeur on a crazy road trip to Edinburgh, Scotland, a trip that helps coax him out of his shell and begin to challenge his tyrannical mother.

Grint, Linney and Walters earnestly embrace the roles, but their characters are so flatly and stereotypically written they come off almost as caricatures of the sensitively gawky youth, the maternal zealot and the outrageous mentor.

Brock comes up with some witty lines for Evie to utter (she accuses Ben of "social autism" and haughtily reveals that when she could not find stage roles, "I was obliged to take TV work.").

Much of the action and dialogue feels forced and affected, though, including the driving lessons Ben's mother puts the boy through, lending the movie a clumsy metaphor for it's title.

It's clearly a very personal little story for Brock, but it's just not that interesting a scenario. Brock dresses it up with some colorful peripheral characters that add little to the story, particularly an elderly boarder who takes to wearing Ben's mom's clothes and winds up at the center of the movie's bizarrely jarring, what-the-heck-just-happened climax.

Aiming to show he can act outside the magical world of Harry Potter, Grint shows a bit more range than the eager-pup persona that Ron Weasley calls for. But either his Ben's too passive or Grint himself is, because the character never really registers emotionally.