Toyota Motor Corp. on Thursday announced a beefed up wireless system for cars that can call an ambulance when an air bag opens, play thousands of karaoke tunes and send a mobile-phone message when a car door is left unlocked.

G-Book Alpha is similar to wireless Internet-linked services offered by other automakers, such as OnStar by General Motors Corp. of the United States. It is an improved version of the service that Toyota began offering in 2002 that has drawn 80,000 users in Japan.

The system is different from rivals in using a telecommunications device contained in the car, rather than a mobile phone, to link to operators, who know where the car is at all times through a Global Positioning System satellite network.

The new system comes with on-demand car-audio called G-Sound, offering drivers more than 10,000 songs stored on the navigation system's hard drive.

Drivers can listen to a song for free for up to 40 seconds three times. Buying a song costs 100 yen to 300 yen. For 700 yen a month, drivers can download karaoke tunes.

"This is like a dream. But some day every car will come with this, although I don't know when," said Senior Managing Director Akio Toyoda.

In a demonstration on Thursday, Toyoda sat in a mock car and an operator's voice shouted: "Mr. Toyoda. Mr. Toyoda," as an air bag inflated.