BMW's US unit is the first automaker to offer a factory-installed digital HD radio (the US equivalent of DAB in the UK and Europe) as an option across its entire 2007 model line.

The option, which costs $US500 now includes multicast reception capability, will be available next spring.

Like Europe's DAB, US HD radio technology provides listeners with enhanced digital audio quality and clear, noise-free reception, as well as multicasting and on-screen text information. The multicasting feature allows FM stations to broadcast multiple channels simultaneously on a single frequency.

Of the more than 1,100 stations across the country broadcasting with the new technology, more than 500 FM stations are offering a second and, in many cases, a third multicast channel.

The number of HD radio stations is growing daily and expected to exceed 3,000 within the next few years.

BMW announced its first OEM availability of HD radio technology in 2005 for its MY2006 7 and 6 Series models.