TOKYO - Toyota Motor Corp. has developed a rear window air bag to upgrade protection for back-seat passengers.

In the event of a rear-end collision, the air bag is ejected from the roof lining above the rear window and spreads like a curtain to protect the heads of the rear passengers.

Toyota said Tuesday the rear window curtain-shield air bag is the world's first.

The new safety gear will debut in the "iQ" compact four-seat vehicle, to be introduced later this year.

As part of an effort to attract buyers, Toyota has tried to make side air bags and shield air bags standard features.