IT SAYS HERE that this latest teen-sex, coming-of-age, gross-out, potty-mouthed road movie is based on a novel.

Pardon? This is rather like hearing that Burger King's current featured sandwich is based on an epic poem, or that your neighbour's septic tank was modelled on a renaissance etching. Do such things really manifest themselves in prose? How enlightening.

Actually, Sex Driveowes its existence to the success of Superbadand more distant antecedents such as The Sure Thing, Risky Businessand Porky's. As you might expect, the shadow of a plot concerns itself with a teenager travelling across country with a mind to losing his virginity.

Ian (Josh Zuckerman), a prototypical good-natured loser, has spent much of his summer cyber-fibbing to a well-breasted lady in a distant state. When she invites him to visit, he piles some pals into his brother's suave car and hits the road.

You know how these things go. The team drink things that should remain undrunk, run over small creatures and embark on ill-advised couplings with various lubricious rednecks. Yet, for all their dissoluteness, they are just looking for respect and affection. It's enough to make you hurl, dude.

To be fair, Sex Drivedoes contain at least two decent recurring comic riffs. Seth Green's turn as puzzlingly sarcastic Amish mechanic showcases that actor's fine comic timing, and the lead's overenthusiastic efforts at humanising a huge plastic doughnut - he wears the costume to advertise a franchise - nearly justify the admission price alone.

Mind you, the best doughnut- related gags are in the trailer and that's available free (and legal) on the internet.

**
Directed by Sean Anders. Starring James Marsden, Josh Zuckerman, Amanda Crew, Katrina Bowden, Seth Green16 cert, gen release, 109 min