General Motors says sales of its Chevrolet Volt electric car will break a monthly record in August.

The company says it already has sold more than 2,500 Volts this month with two days left. The old record was 2,000 in March.

A spokeswoman says about one-third of the sales are in California, where Volt owners can drive alone in carpool lanes. She says sales are growing in other states.

So far this year GM has sold more than 13,000 Volts. The car can go about 35 miles on battery power before a small gas generator kicks in to keep it moving.

Earlier this week GM said it will close the Volt factory in Detroit next month to control inventory and retool the plant to build the new Chevrolet Impala.