They’ve already sold many more units this year than they did last year, thanks in large part to a little help from the California legislature. Not only do you get to use car-pool lanes there if you’re driving a Volt, you get a $1,500 state rebate on top of your $7,500 federal tax credit. Don’t underestimate government’s ability to make this overpriced novelty popular by piling incentive upon incentive to induce you to buy it. All Congress needs to do is pass a law granting the Volt a special speed-limit exemption on the interstate and GM might be viable again.

As for now, though, even with the increase lately, the company still can’t sell enough cars to justify running the plant all year round:

GM will close its Detroit-Hamtramck plant from Sept. 17 until Oct. 15, one of the sources said. Union representatives last week told the plant’s roughly 1,500 workers about the scheduled downtime, the source said…

Volt demand has picked up this year, after sales last year fell short of GM’s goals. GM sold 10,666 Volts through July, more than triple the 2,870 sold during the same period a year earlier.

GM executives have attributed the sales increase to strong demand for a low-emissions version of the Volt that qualifies for California’s coveted carpool lanes, which GM launched in March. Previous versions of the Volt didn’t qualify.

Volt inventories have been whittled down, too, to 6,500 units, or 84 days’ worth, as of Aug. 1. On March 1, just before the last production shutdown, GM had 154 days’ worth.

They shut the plant down from late March to late April too. Believe it or not, at one point earlier this year, they were hoping to sell 45,000 Volts in the U.S. alone. Yeah.

Exit question: is GM headed for bankruptcy — again?