In the latest boost to its dominance in portable music players, Apple Computer Inc. (AAPL) is teaming with General Motors Corp. (GM), Ford Motor Co. (F) and Mazda Motor Corp. to integrate the iPod into car audio systems.

GM and Ford are the nation's No. 1 and No. 2 automakers, and the new alliances mean the iconic audio gadget will now be compatible with more than 70 percent of the new 2007 model vehicles sold in the United States, Apple said Thursday.

GM and Mazda will offer iPod integration on all new models, Apple said, and Ford will offer it on many of its Ford and Lincoln Mercury models later this year.

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Carmakers say they are responding to a booming trend in which sales of iPods and other MP3 players are predicted to more than double from 58 million units in 2005 to 132 million in 2009.

The iPod holds about a 75 percent share of the portable player market in the U.S.

Working with the iPod maker is part of increasing effort by Ford and other car companies to make it easier on drivers to access a variety of gadgets — from cell phones and navigation systems to music players — while on the road.

"Consumers are listening to music, they're messaging each other, and they want to engage in all those activities in their vehicles but in a safe manner," said Doug VanDagens, director of Ford's product and business development in the electronics group.

Germany's BMW AG two years ago incorporated iPods directly into its car audio systems, allowing users to plug the music player into an adapter that goes into the glove box and access the iPod's music library through the car's standard controls.

By last fall, as sales of the iPod continued to surge, Apple had signed similar deals with about a dozen more car companies, including Acura, Audi, Ferrari, Honda, Nissan and Volkswagen.

Ford said Thursday it will offer the iPod integration as a dealer-installed option called "TripTunes Advanced" at a suggested price of about $200, plus installation.

An adapter that doubles as a battery-charging station would go in either the glove box or center storage console. Users would then be able to control the iPod through buttons on the steering wheel or the radio. Playlists, artists, and other song information will also be displayed on the cars' systems.

In addition, Ford plans to add auxiliary audio input jacks on nearly half its lineup, starting this fall. Tunes from any gadget — iPods, other MP3 or CD music players, cell phones and game handhelds — will then be playable on the cars' audio systems without the need for extra adapters or FM transmitters.

Demand for built-in satellite radio features has also prompted Ford to expand its relationship with Sirius Satellite Radio Inc. (SIRI) VanDagens said more than 90 percent of Ford and Lincoln Mercury cars will offer satellite radio by the 2008 model year.

GM said it will offer its iPod-only setup called "Personal Audio Link" at dealerships for all 56 of its models at a suggested retail price of less than $160, plus installation.

"We know our music-loving customers have been clamoring for a system like this, but we were determined not to go into the market with one unless it was truly integrated, easy to use and affordable," said Nancy Philippart, executive director of GM accessories. "I think this system will be music to our customers' ears."

Indeed, analysts say U.S. automakers are once again lagging behind foreign companies in new features, but in this case, "at least they're finally getting more attuned to what consumers want," said Art Spinella of CNW Marketing Research.

The new iPod option particularly could help struggling GM, which has been attracting younger customers in recent years.

"It won't translate into sales in a dramatic way, but it certainly keeps customers from discarding the brand or its cars while shopping," Spinella said.

GM lost $10.6 billion last year and is under threat of losing its title as the world's largest automaker.

Ford also has been losing market share to Asian manufacturers for a decade and has been badly stung by high gas prices because big trucks and sport utility vehicles account for a majority of the vehicles it sells.