Q: What's the difference between high-end prostitution and sub-prime mortgage loans?

A: Not much, really.

Both of those lucrative "financial instruments" substitute illusion for reality -- short-term fun and profit for long-term security -- especially in 2008. The election and economic meltdown of that year serve as backdrop for a wicked little update, of sorts, to director Steven Soderbergh's groundbreaking debut film, "sex, lies and videotape."

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'The Girfried Experience'

3 stars = Good
Ratings explained

• Starring: Sasha Grey, Chris Santos
• Rating: R for sexual content, nudity and language. Opens at the Manor today.
• Web site: http://www.girlfriendexperiencefilm.com/

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This one could be titled "sex, truth and DVDs" instead of "The Girlfriend Experience." It's the story of winsome Chelsea (Sasha Grey), an ultra-chic Manhattan call girl who commands $2,000 an hour while enjoying a "committed relationship" with Chris (Chris Santos), a well-buffed personal fitness trainer who is fully aware and supportive of his girlfriend's occupation.

Chelsea's professional secret -- key to the success of her "escort" business -- is that she acts like a girlfriend-shrink instead of a hooker, providing an ever-so-sympathetic ear and ever-so-ersatz emotional intimacy beyond the sex act itself (which many of her clients never even get around to).

But '08 times are suddenly much tougher, and "post-crisis capitalism" offers no government bailouts for prostitutes. Chelsea and Chris need more income. To that end, she consults various sex-biz advisers on "growing her business," and he angles for a better gym gig, with problematic results: A client named Philip triggers Chelsea's long-suppressed longings and Chris' jealousy -- trouble in previous paradise.

Stylishly shot with natural and real-source lighting in an artsy cinema verite style, "Girlfriend" was made on a shoestring budget in just two weeks, blessed with a piquant script full of semi-improvised, semi-satiric dialogue. ("We've been together almost a year and a half!" Chris moans. "Are you gonna throw all that out?")

It may or may not be so blessed with a cast of non-actors, chief among them the erstwhile porn-film star, Sasha Grey, in her first "real" movie role. Miss Grey, the Penthouse Pet for July 2007, is the winner of a variety of adult video best sex scene awards.

For one whose past credentials bespeak a stunning lack of inhibitions, Grey is oddly low-key -- undynamic verging on somnambulistic -- with a mumbly, monotonic delivery. I suspect those are precisely the qualities that appealed to the director's sense of irony in casting her. She is not particularly beautiful, either (and don't expect to see much of her flesh). All of which is not to say she's terrible, just diffident. In any case, I don't think this is going to be her breakthrough film.

Santos, on the other hand, is vibrant in his debut. But the best performance is a cameo by Premiere mag film critic Glenn Kenny, playing a hilariously sleazy "erotic connoisseur" (Web sex critic). He requires sample sex for his reviews, and, when Chelsea declines, he viciously pans her "flat assets, lack of culture and utter refusal to engage -- she couldn't even dazzle Forrest Gump!"

Actually, he's kinda right-on.

Since "sex, lies and videotape" (1989), Soderbergh has alternated between his independent path and the Hollywood machine: from the brilliant "Schizopolis" (1997) to "Erin Brockovich" and the Oscar-winning "Traffic" (both 2000) through those mundane "Ocean" films and ambitious two-part "Che." "Girlfriend" represents his homage to Godard and the American New Wave of the '70s -- a character study in the Cassavetes tradition, as well as an Altman-type comedic drama. Or dramatic comedy? I'm not sure. But it's sharply edited, with his trademark voice-overs overlapping from one scene to the next, and it comes in at a crisp 77 minutes.

The subject of this downbeat, cynical exercise is not really sex but economics. The degree to which it's touching, depressing or amusing is in the eye of the beholder.

The moral is an immoral variation on the Stones: You can't always get what you want OR what you need -- just what you pay (or have been paid) for.