Toyota sold more Prius Plug-Ins last month than Chevrolet did Volts or Nissan did Leafs.

Toyota quietly introduced the plug-in version of its Prius hybrid earlier this year, and despite its limited fanfare, it is already outselling the Chevrolet Volt.

Last month, Toyota found 1,654 buyers for its Prius Plug-In, which accounted for about 7 percent of its total Prius line sales, according to Green Car Reports. By comparison, Chevrolet delivered 1,462 Volts and Nissan sold a mere 370 Leafs. While the Leaf is entirely electric, analysts and members of the media often group it with the Volt and Prius Plug-In, both of which offer the ability to travel for a moderate range on EV power alone before a gasoline engine kicks over.

Part of the Prius Plug-In's appeal might be its lower price. While a Volt starts just shy of $40,000, the Prius Plug-In lists from $32,000. That extra $8,000 for the Volt buys about triple the EV-only range.

In addition to the "classic" Prius liftback, Toyota now also sells a compact hybrid called the Prius c and a larger model called the Prius v. In its sales reports, Toyota groups all four Prius models together, even though the c shares little with its bigger brothers and the v features a different body.

Although Toyota hasn't released market-specific data for the Prius Plug-In, it's possible that California's recent ruling to allow plug-in hybrids - but not conventional hybrids like the rest of the Prius line - access to carpool lanes might have worked in Toyota's favor. By a wide margin, California is Toyota's strongest market for the Prius.