It is one of the great mysteries of the music universe.

For three years, fans of the L.A.-based, keyboard-rock band the Rentals have wondered, just who is "P," the inspiration for the group's 1995 hit "Friends of 'P' "?

Now, the truth can be told.

As the group prepares to release its eagerly awaited sophomore album, Seven More Minutes, leader and former Weezer-bassist Matt Sharp agreed to spill the beans. (A full-length interview with Sharp -- which will include three, never-before heard tracks from the Rentals' upcoming LP -- will run in the new issue of Addicted To Noise, online Tuesday.)

"That was one of the first songs I ever wrote, in the infancy of the Rentals," said Sharp, 28. "And the song's all about Paulina Porizkova," Sharp explained, exhaling, as if a great weight was lifted from his shoulders.

Porizkova is the supermodel wife of former Cars singer/guitarist Rick Ocasek, who produced Weezer's 1994 self-titled debut.

"I think at the time it came about because she had mentioned that the only people who would write songs for her were bad heavy-metal bands or something like that and all her friends were getting these songs written about them," Sharp said.

Sharp and Rentals guitarist Rob Cervera said once the offhand song became a radio hit, they were suddenly inundated with potential explanations for the tune's cryptic refrain, "If you're friends with 'P'/ Well then you're friends with me."

While Cervera, 27, said he decided just to let people draw their own conclusions about the mysterious "P," Sharp expressed amazement at the range of potential answers.

"The whole thing started accidentally, and it just got blown out of proportion," Sharp said. "It became, 'Oh, this is this big secret,' and it go so f---ing funny and surreal."

Fans wrote in with explanations that ranged from funny, celebrity-themed guesses to sad theories, such as the fan who wrote in suggesting the song was about Parkinson's disease, according to Sharp.

"He thought it was about Parkinson's and his grandfather and maybe one of us had been through that kind of scenario," Sharp said.

And although the character of "P" makes a cameo appearance in the lyrics to one of the most experimental songs on the upcoming Rentals album, the funky, rap-tinged "Big Daddy C," this time "P" is a whole different animal. In the song, a voice is heard asking, "Who the hell is 'P'?"

"It means something; I wish I could explain it," Sharp said, perhaps unleashing another mystery. "It's not about her, she doesn't have anything to do with the new song. It's about her friends, I guess."

More an extension than a sequel to the group's hastily recorded 1995 debut album, the nearly double-platinum (2 million in sales) Return of the Rentals, Seven More Minutes expands the group's kitschy new-wave keyboard-rock sound with lush, sometimes-aggressive and, most importantly for Sharp, revealing tunes.

The album's release will come more than six months after it was announced that Sharp would be leaving his position as Weezer's bass player.

The bass-plucker-turned-frontman said he already can't wait to get back out on the road and test the more fleshed-out material on his new album. It's the first record he's played on that really captures something essential about his life, he said.

"The first album was done in a very strict way," Sharp said. "The way the synths were used had a pattern that fit every song and I like records like that a lot, I think that's good for first records. But by the time we got in the studio for this one it felt like we could do anything."

While the itinerant lineup for Seven More Minutes brought back such first-album alumni as keyboardists Grimley and Jim Richards, guitarist Cervera and backup singer Petra Haden (ex-That Dog), Sharp also managed to enlist an all-star cast of British pop luminaries.

Among the notables dropping by are Elastica bassist Donna Matthews -- who sings smoldering back-up on the sultry mid-tempo track "Say Goodbye Forever" and duets with Sharp on "Must Be Wrong" -- as well as Blur leader Damon Albarn, who lends vocals to "Big Daddy C."

Also checking in is Ash guitarist/singer Tim Wheeler, who sings harmony on the upbeat, Weezer-like keyboard-rocker, "Hello, Hello." Wheeler also plays acoustic guitar on the album's emotional centerpiece, "Overlee," a strident keyboard-and-acoustic-guitar anthem about blissful dislocation. "Where there's no language and there's no country/ I want to take you to Overlee," Sharp and Haden sing in perfect harmony on the track.

The full track-listing for Seven More Minutes is: "Getting By," "Hello, Hello," "She Says It's Alright," "The Cruise," "Barcelona," "Say Goodbye Forever," "Overlee," "Big Daddy C," "Keep Sleeping," "The Man With Two Brains," "Must Be Wrong," "Insomnia," "It's Alright - Reprise," "My Head Is In The Sun" and "Jumping Around."

The album, due in early spring, does not yet have a firm release date.