General Motors will suspend production of the Chevrolet Volt extended-range electric vehicle for five weeks, beginning March 19, to manage rising inventories of the one-of-a-kind car.

“We are taking some downtime to ensure proper inventory levels,” says GM spokesman Chris Lee.

Chevy Volt production resumed Feb. 6 after a prolonged holiday shutdown.

GM sold 1,023 Volts in February, the car’s best month since delivering 1,529 units in December, WardsAuto data shows.

However, inventory closed the month at an all-time high of 6,319 units, or a 154-day supply, including vehicles in transit. GM says dealer stocks sit at 3,596 units. The typical inventory level for a vehicle is 60 days. In January, supplies of the Volt hit 222 days.

WardsAuto learns GM also is considering a longer summer shutdown, perhaps as many as four weeks, at the Volt’s Detroit-Hamtramck assembly plant.

Auto makers historically idle assembly plants for two weeks between June and July to accommodate model-year changeovers. Last summer, GM suspended Volt production for four weeks to retool for the ’12 models.

A cornerstone of the restructured auto maker’s comeback plan, the Volt did not live up to initial 2011 production estimate of 10,000 units. At its current pace, it will reach that number next month.

GM wants to build 60,000 Volts this year for the U.S., with 15,000 for foreign markets although deliveries to Europe were held up due to a U.S. safety probe. In 2011, it cranked out 14,510 units.

The auto maker intended to add a second shift at Detroit-Hamtramck last year to accommodate Volt production, but has since held back on those plans, saying changes to the car’s assembly process sped up builds. It was looking to add that shift in the second half of this year.

GM had hoped the Volt would boost its post-bankruptcy image. The car has drawn positive reviews and owners steadfastly defend its ability to slash fuel consumption.

But it also has become a “political punching bag,” as GM Chairman and CEO Dan Akerson told a Congressional panel last month examining whether the National Highway Traffic Safety Admin. covered up a fire involving the Volt’s battery pack after a government crash test.

NHTSA was absolved of any shenanigans, and the Volt has been declared as safe as any vehicle on the road. Conservative critics continue to attack the vehicle as a white elephant created by the Obama Admin. and its 2009 bailout of GM.

The auto maker previously has said that inventory constraints were behind the car’s tepid sales, not its $40,000 sticker price.

GM North America President Mark Reuss said last month that the battery-fire controversy would hurt sales in the short-term. At the recent Detroit auto show, he told WardsAuto the auto maker would keep Volt production in line with demand, whatever the consequences of public opinion.

GM learned earlier this year the Volt would qualify for California’s high-occupancy vehicle lanes, allowing owners to commute more quickly around the state’s traffic congestion when traveling alone.

HOV access helped propel popularity of the Toyota Prius, a primary competitor of the Volt, in its early days. The Prius now ranks as one of the best-selling cars in the U.S. and has made Toyota the greenest auto maker in the public’s eye.

The Volt can travel up to 50 miles (81 km) on electric power before an internal-combustion engine takes over to give it a full range of about 320 miles (515 km) before it must be recharged or refueled.

jamend@wardsauto.com