Nissan sold 931 all-electric LEAFs in July, while numbers of just 125 Volts sold last month makes July 2011 the worst month for the Volt since being introduced last year.
Nissan has sold 4,806 units in 2011, or total of 4,825 LEAFs in the United States since it began shipping them in December.
Meanwhile, GM has sold 2,870 Chevrolet Volts in 2011 or 3,196 units since launching late last year.
GM says the decline in sales is mostly because the plant where Volt is produced has been shut down for upgrading. GM expects to sell around 16,000 Volts by the end of the year in all 50 states now that the plant has re-opened. In 2012, Volt is expected to reach a global production capacity of 60,000 vehicles, with 45,000 of to be sold in the U.S.
Nissan has said 20,000 people have put down $99 deposits to be put on a waiting list for the car. Japanâ€™s second-largest carmaker, aiming to be the worldâ€™s largest seller of electric cars, expects to deliver as many as 12,000 LEAF electric cars to U.S. customers this year.