Mazda, GM and Ford are to introduce iPod adapters allowing the iconic personal music players to be operated through factory-installed audio systems.

Mazda's device will be launched in Japan on 22 August and will later become a dealer option world-wide.

Mazda claims to be the first to offer iPod adapters for almost all of its models to be launched in the future.

The device costs JPY23,100 (£107.00, $US201) including installation and tax in Japan.

GM will also offer iPod integration on all new models, the music player's maker Apple told the Associated Press (AP), and Ford will offer it on many of its Ford and Lincoln Mercury models later this year.

The new alliances mean the audio gadget will now be compatible with more than 70% of the new 2007 model vehicles sold in the United States, Apple told the news agency.

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

The iPod holds about a 75% share of the portable player market in the US, AP noted. 

"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," Doug VanDagens, director of Ford's product and business development in the electronics group, told the news agency.

BMW 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, the report said.

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

According to AP, Ford said on Thursday it would offer iPod integration as a dealer-installed option called "TripTunes Advanced" at a suggested price of about $US200, 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 autumn, the report added. 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.

GM reportedly 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," Nancy Philippart, executive director of GM accessories, told the Associated Press. "I think this system will be music to our customers' ears."

Analysts have told the news agency that US 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," according to 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 told AP.

Chrysler Group's new Dodge Caliber hatchback - which replaced the Neon sedan earlier this year has a centre console holder for an iPod or other music player (or a mobile phone) and offers an aftermarket adaptor to hook the player to the factory-fitted audio system.

Ironically, the new model has been criticised by some consumer writers for deleting the auxiliary socket that allows a music player to be plugged in from the optional high-end audio unit.