HERNDON, Virginia — Audi plans to include HD Radio as standard equipment on many of its vehicles beginning with the 2011 model year. Those cars will begin arriving in dealerships in 2010.HD radio delivers free, higher-quality sound along with text information including song titles, artist names, real-time traffic and weather, movie listings, sports scores, stock quotes, school closings and emergency alerts. Additionally, HD Radio offers more channels. There are more than 1,800 AM and FM stations currently broadcasting in HD Radio. Nearly 900 of those stations are broadcast on HD2 and HD3 channels that aren't available on traditional radio.Audi currently offers Sirius Satellite Radio as standard equipment in its cars. Come 2010, both Sirius and HD Radio will be standard fare on Audis.Inside Line says: Audi's widespread adoption of HD Radio may go a long way toward pushing the technology into the mainstream. — Eric Tingwall, Correspondent