Long before its nationwide launch last November, the creators of XM Satellite Radio talked a big, bold game. We’ll do for radio what cable did for TV, they promised. We’re the first fresh idea in radio since FM was a fuzz-cheeked lad, they boasted. But as the man said, it ain’t bragging if you can back it up. So far, Washington, D.C.-based XM has justified the hype with 100 channels of CD-quality sound beamed from its two satellites, aptly named Rock and Roll, to cars equipped with satellite-ready receivers and antennas. A subscription costs $10 a month; equipment and installation can run $300.

For that, you get 71 channels of music (34 sans commercials) swinging from reggae to gospel, rap to opera, bluegrass to Latin jazz, movie soundtracks to big-band beats. XM rounds out the lineup with news, sports, talk, and children’s programming. Most reviewers have joined the chorus of praise for XM, which quickly added another line to its brag sheet: The company says that selling 30,000 subscriptions in its first 60 days makes XM “the fastest-selling audio product of the last 20 years,” outstripping music CDs and DVD players.

Such claims are hard to prove or refute, but XM’s intriguing, eclecticus-maximus formula is for real — and many observers see its timing as perfect. Rampant consolidation in the radio industry has led to repetitious, cookie-cutter formats from Oregon to Orlando. Having built these huge radio conglomerates, the moguls must pay for them by increasing the commercial load, which means less programming, which means more frustrated listeners.

XM officials say they can make a profit with 4 million subscribers — less than 2.5 percent of the nation’s 200 million registered vehicles. But by this summer, rival Sirius Radio will complete its own national rollout, setting the stage for a satellite smackdown. As they say in radio, stay tuned.