Toyota cars in Japan will soon sport up-to-date roadmap and traffic data so drivers can instantly learn the quickest routes.

Toyota Motor Corp. said the service will include a "map on demand" with constantly updated information on the nation's roads. The car maker will roll out the technology next month in all new models sold in Japan.

The basic offering, G-Book mX, uses a cell-phone connection and is free. The driver needs to buy navigation equipment and pay the phone bill. The more advanced G-Book mX Pro comes with an on-board data-transmission device. Costing $100 annually after a free year, it has extra features such as automatically alerting authorities when an air bag inflates.

Besides constantly updating map data that's available in the car, the service tracks how quickly cars are moving and sends the information to a central computer system. That way, traffic congestion can be factored in when the device is calculating routes, Toyota officials said.

The new service is more accurate than the electronic route-mapping systems now available, they said, because it has access to information collected from thousands of Toyota cars on the road.

All the world's automakers offer versions of such services, but they tend to target luxury car owners and aren't as zealous about delivering the latest updates.

Toyota Executive Vice President Akio Toyoda said a similar service will be offered in China but did not say when. Plans in the United States and other foreign markets are still undecided.