Maybe on paper - a cocktail napkin, perhaps, but certainly not the shooting script - The Guilt Trip seemed like a good idea. Take a geeky grown-up with no dating or mating skills and put him in a car for a cross-country road trip with his smothering, motor-mouth mom.

Cast Seth Rogen, the mumbly, deadpan doofus of a hundred Apatow-ian comedies, and Barbra Streisand, the Hollywood icon and ace screwball star of What's Up, Doc? fame, and what could go wrong?

Well, nothing actually goes terribly wrong in The Guilt Trip, it's just that nothing goes terribly right, either. The Dan Fogelman (writer) / Anne Fletcher (director) film, which winds its way from North Jersey to northern California, is all-too-evocative of a real-life road trip: moments of illuminating talk, of promising pit-stops to take in the great sights or enjoy an unexpectedly delicious meal, interspersed with interminable stretches of tedium.

Rogen is Andy Brewster, a science-nerd inventor who is trying to sell his environmentally friendly cleaning product to a big chain. His social skills and salesmanship talents, alas, are sorely lacking, and he's fast sinking into debt.

Streisand is Joyce, a widow, and a proud but puzzled mother who can't understand why her son can't find a beautiful young woman to settle down with. When, during a holiday visit home (Andy has moved from Jersey to L.A.), Joyce reveals a deep secret regret from her own romantic past, Andy decides to help her out. Hence, the invitation for Joyce to join him on his drive back to the West Coast, with stops for pitch meetings along the way.

The Guilt Trip has a couple of funny, or at least eventful, set pieces. There's a contest at a Western-style eatery where Joyce attempts to down a 50-ounce steak and accompanying meal while the clock ticks to zero (suspense, finally!), and Andy's audition with the Home Shopping Network doesn't go quite as expected, and that's a good thing. The audio book Joyce has brought along for the ride also supplies a few awkward, embarrassing ha-has: It's Jeffrey Eugenides' transgender saga, Middlesex.

Over the 3,000-mile journey, the Brewsters' little rental pulls into a strip club, into the home of one of Andy's high school sweethearts, into the corporate offices of Kmart (and a few other product-placement-ready outfits), and into Las Vegas, too. And then there's a stop at the Grand Canyon (which looks real), and a visit to a house on a block of Victorians in San Francisco (which looks more like L.A.).

Are we there yet?

The Guilt Trip ** (out of four stars)

Directed by Anne Fletcher. With Seth Rogen and Barbra Streisand. Distributed by Paramount Pictures.

Running time: 1 hour, 35 mins.

Parent's guide: PG-13 (profanity, adult themes)

Playing at: area theaters EndText