DRIVING LESSONS — * 1/2 — Rupert Grint, Julie Walters, Laura Linney; rated PG-13 (profanity, vulgarity, violence, brief drugs).

If the makers of "Driving Lessons" put half as much effort into creating believable characters as they did in attempting wacky comedy, they might have had something special. Instead, the characterizations and comic situations both seem forced and labored.

Also, some of the film's content was edited to get it a more audience-friendly PG-13 rating in the United States, though it's still surprisingly vulgar and crass.

Consequently, this is not exactly what you'd consider to be an ideal vehicle for Rupert Grint, co-star of the "Harry Potter" movies.

He stars as Ben Marshall, a shy Scottish teen who's constantly at odds with his overbearing mother, Laura (Laura Linney). He's also painfully inept when it comes to dealing with girls.

Recently he's taken a job as an aide to Evie Walton (Julie Walters), an eccentric, retired actress. As batty as she is, Evie does begin coaxing Ben out of his shell and even forces him to drive her to an out-of-town engagement. However, his mother begins worrying about the amount of time her son is spending with the older woman.

Screenwriter-turned-filmmaker Jeremy Brock tries to do everything he can to make us dislike the mother, a one-note construct that defies even Linney's best efforts. However, the Walters character is such a kook that you can certainly understand her concerns. (This is not Walters' most subtle performance, to put it mildly.)

As for Grint, he seems a little uncomfortable and out of sorts. Not that you can blame him — especially considering the sexual frankness and crudity of some of this material.

"Driving Lessons" is rated PG-13 for some sexual language (profanity, slang and other suggestive talk), some vulgar toilet humor and references, brief vehicular violence and brief drug content (references to prescription medicines). Running time: 98 minutes.

E-mail: jeff@desnews.com