ELEVEN YEARS AGO, a strapping 18-year-old guitarist and singer named Christopher Geppert crammed his 6-foot-2-inch frame into a station wagon in Austin, Texas, and drove to the airport to pick up a band of up-and-coming British blues rockers named Fleetwood Mac.

Geppert had been singing and playing guitar since seventh grade, and was working as a "gofer" for concert promoters, learning the music business firsthand. That night he played chauffeur, driving the Macs to restaurants and showing them the town.

This year, Christopher (renamed) Cross was the opening act on tours by Fleetwood Mac and the Eagles. And on Wednesday, while those two groups sit out this year's Grammys, Cross will stand nominated in eight categories, including the prestigious "Best New Artist."

His smooth-sounding, pop-and-roll debut, "Christopher Cross," was Warner Bros.' biggest-selling album of the year (3 million copies) and has yielded two No. 1 singles (the breezy "Ride Like the Wind" and lush "sailing"), and one No. 4. Moreover, the album has clung to the top-20 sales charts for 49 weeks: a remarkable achievement for a first effort in this year's sagging record business.

Of his Grammy chances, the soft-spoken Cross says only, "I'm just going to go, sit there and smile a lot." The nominations and platinum sales now represent "old dreams," he says. "The sales validate my commercial acceptance. But the Grammy awards come from people in the same business, with the same experiences."

Cross, 29, is less cocky than confident, an Army brat who grew up in Japan and Washington, D.C. before returning to make his home in his birthplace of San Antonio. Reached while on tour last week, he was matter-of-fact about his success. "I write quality music and it's commercial and I have a good voice -- but those are elements that run in other people's music, too. As far as 'Why me?' I don't know. Whoever was on our team, I'm thankful. I'm glad they were."

Some of those people inlude producer Michael Omartian (Steely Dan) and engineer Chet Himes (both up for technical Grammys), singer Michael McDonald of the Doobie Brothers, Nicolette Larsen, Don Henley of the Eagles and J.D. Souther. Just as important were the 700 hours Cross spent in the studio experimenting with a 48-track set-up, developing the bright commercial pop sound that's dynamic on the radio.

But Cross (who writes and sings all his own material and is signed as a solo act, though the band also bears his name) didn't spring on the industry full-blown. He paid his dues with 10 years in Texas copy bands, playing other people's hits to bar crowds. "I hate to even use the term," he says in his nondescript accent, "but we were . . . whores. We just played what everybody wanted to hear. My material was in my guitar case, but people didn't want to hear it. We played what could make us the most money. . . $150, $200 a week each. It was meager but it was steady. When disco came in, we were a disco band."

Being a living radio "did give you a way of singing and playing a variety of styles of music, different licks. And sometimes, we'd try to aspire -- like learning a Weather Report song for a break." But mostly the band played a lot of Eagles, Fleetwood Mac, Led Zeppelin, Ted Nugent. "When Barbra Streisand's 'Evergreen' came out, I sang that, too. We'd cover whatever." These days, copy bands are learning Cross' music, while the rookie finds himself competing with the veteran Streisand for the big three Grammys (record, album and song of the year). The songs in the bottom Cross' guitar case were at once unique and derivative of other commercial sources: a little bit of sophisticated rock a la Steely Dan and Fleetwood Mac; country-rockish gleanings from the Eagles and the Marshall Tucker Band; the sincere choirboy vocals of Danny O'Keefe and Todd Rundgren. Cross' publishing company is called "Pop and Roll," and it's the mechanical pop craftsmanship implied in that name that irritates his detractors.They claim his archetypal easy-listening rock -- one critic blasted its "overly ingratiating, blow-dry feel" -- is precisely the bland posturing the Grammys like to reward.

"That's all I can do", Cross insists. "When I sit down and write songs, that's how they come out. I just think of hooks.My main infuences were the Beatles in the '60s, Buddy Holly, Steely Dan . . . they tended to write that way. We're really just playing '60s music all over again."

Cross first adopted his new name when he released a privately pressed regional single in 1970 (it's now a collector's item). It's stuck ever since, blessing him with a private life under his real name. He started sending demo tapes to record companies in 1975. Result: rejections. "I thought they were idiots passing up the chance of a lifetime," he laughs now, "but looking back on it, the music wasn't mature enough and I wasn't ready. I'm glas they didn't sign me, I might have become one of the unknown soldiers.

"But I'll tell you, we used to finish up those demos in the middle of the night, and stand out there in the street, confident. By '77, there was some more serious interest and a 1978 tape got Warner Bros. to come down for a showcase of our original material."

The lean years were cushioned by family support. Cross' father and three uncles were doctors, his mother a nurse; he himself went into pre-med, even giving up music for a while to "study hard for a couple of years. But I told my father 'I don't really like this, I want to jam out.' My father had played bass in local bands in college and really enjoyed his experience in music. He used to say those were the happiest times of his life. So he told me, 'Don't be what you don't want to be. You've go to live with it the rest of your life. Go for it!'"

Cross' wife of seven years and his son Justin (now 4 1/2) also weathered "some frustrating financial times. But Roseann never asked me to give it up when I let the copy thing fall." One of the burdens Cross had to bear was the industry's concept of Texas music. "People expect boogie, blues or country," he says exasperatedly. "I love Texas and have spent most of my life here and there's so much good music that's not like that."

If Cross doesn't have the stereotypical Texas sound, he has the size. When Houston Oiler fullback Earl Campbell's manager gave Cross Campbell's Oiler jersey, the singer easily filled it. "I've always been big framed. They always wanted me to play football but I was too busy playing guitar."

Cross' sturdy looks have led to speculation that Warner Bros. purposely avoided putting his picture anywhere on the debut album to obscure the seeming incompatability between his big bones and the gentle, swaying "feelgood beat" that seem tailor-made for radiopop. This draws a guffaw from the singer. "I'm never going to be little. I look the way I look and there's nothing I can do about it. I don't think I'm ugly -- I think I look great." He admits that people sometimes expect him to look like Jackson Browne or Kenny Loggins . . . or Michael McDonald.

"I'm sure there's girls who are dissappointed when I come out on stage, but I just don't go in for that kind of thing. If I'm not the image and they don't want to buy my music for that, then I'm sorry and I don't want them for fans."

The McDonald connection is another part of the story. The Doobie Brothers' lead singer was a friend of producer Omartian's from the Steely Dan days, and he agreed to listen to some Cross tapes; apparently liking what he heard, he ended up singing on two cuts. "That started the ball rolling," Cross says. Next in was Nicolette Larsen, who was working on a Randy Newman session in the studio next door; she was followed by guitarist Larry Carlton and singers Souther, Henley and Carter. "But they wouldn't have sung for a new artist if they didn't like it," Cross insists. "You couldn't pay them, they're already rich."

The Cross/Larsen cut, "Say You'll Be Mine," was originally scheduled as the first single for Cross' debut album; it was even pressed and ready to ship. "But Omartian decided that with disco still happening, we should come with a danceable beat for crossover." So Warner Bros. picked the Cross/McDonald duet on "Ride Like the Wind", and it stormed to the No. 1 spot on the singles charts. "Say You'll Be Mine" came out third and went to No. 4. In between, Warner Bros. had been set to release "I Really Don't Know Anymore," another cut featuring McDonald -- until the Doobies, who also recorded for Warner Bros. and were about to release their new album, pushed to hold it back.

"Michael had been doing a lot of background vocals and was overexposed on the radio. The Doobies got concerned that it was going to hurt their record, so we came out with 'Sailing' instead," Cross explains. It too ran to the top spot on the charts, diluting any anger the new artist might have felt. "That was probably the best thing that ever happened," Cross says happily, "because it gave me my own identity. There's noboby else on the record."

For now, Cross is riding out the wind of his own surprising success. His major problem is that as a sudden headliner, he only has 40 minutes -- one album's worth -- of familiar material to play for audiences. There's no sense rushing out a second album until the first has peaked; for now, it looks like an April return to the studio. The touring has been consistent, which has left little time for songwriting, so a break will follow the Grammys, too. Ultimately, he wants to get into producing . . . other people. "You need an objective ear on the other side, you get too close to it otherwise. It would be a foolish move to produce myself."

He also vows to remember his brief career as Fleetwood Mac's valet. "I'm not going to make mistakes with people. I'm a good guy but I can also get tired and cranky. But I remember that feeling of intimidation. To some people, it's a big deal to come into contact with a big name or a star. I try to remember how I felt."