TOKYO -- Toyota's Prius hybrid was the top-selling car in Japan in September for the fifth straight month, helped by tax breaks and government incentives for 'green' vehicles, an industry group said Tuesday.

Toyota Motor Corp., the world's biggest automaker, sold 31,758 Prius cars last month, according to the Japan Automobile Dealers Association.

Toyota said this week there was a backlog of Prius orders, numbering in the several thousands. Customers ordering the cars now won't get them delivered until after May 2010. Some ecological subsidies are scheduled to end March 31, 2010.

Honda Motor Co.'s Fit compact was No. 2 in September for the sixth month straight with 17,241 sold.

Energy-efficient vehicles, including gasoline-engine models like the Fit, get perks such as zero or lower taxes and other green subsidies in Japan.

Honda's Insight hybrid, briefly No. 1 in April before the remodeled Prius rolled into showrooms, was No. 5 in September.

The Prius was the top-seller for the first half of the fiscal year through September, with 116,298 vehicles sold in Japan.