March was another good month for U.S. sales of the Nissan Leaf, the best-selling electric car in the world.

In fact, March was a good month for several plug-in electric cars, with monthly sales up for many models, and new monthly records for a few.

Roughly 9,000 electric cars were sold in March, against about 6,900 in February--an increase of almost one-third, which may bode well for the balance of the year.

Market leaders

Nissan sold 2,507 Leafs in March, bringing its three-month total to 5,184--logging a 12-percent increase over the 2,236 sold in March 2013, the first month in which U.S.-built Leafs were sold in any number.

The March number was the single highest March sales total for the Leaf since it went on sale in December 2010, and the second-best month. Sales in December 2013 were 2,529--or just 22 cars higher.

The March deliveries bring total Leaf sales in the U.S. to 47,306, and the number of plug-in electric vehicles on U.S. roads is likely to cross 200,000 sometime next month.

MORE: Plug-In Electric Car Sales For Feb: Leaf Up, Volt Down (Tesla Unknown As Usual)--FINAL UPDATE

Embattled General Motors--whose CEO Mary Barra is testifying before Congress today about a growing range of recalls for safety defects in GM cars built before 2010--suffered from a computer outage on the morning of the 1st that prevented it from tallying and releasing its monthly sales data for most of the day.

When sale figures were finally released, March delivers of its Chevy Volt range-extended electric hatchback were 1,478--its best monthly total since December and, oddly, identical to the 1,478 units it sold in March 2013 as well.

Cumulative Volt sales for the year thus far total 3,296, keeping it only a few hundred behind the chart-leading Leaf.

The Volt remains the plug-in electric car with the highest U.S. sales to date, at roughly 58,200 Volts versus 47,300 Leafs. But Nissan has said it plans to boost Leaf sales volume throughout 2014.

Will the Leaf capture the title for highest total plug-in model sales since 2010 by the end of this year? It might happen, but it promises to be a battle to watch.

As for the Tesla Model S, the startup electric carmaker doesn't deign to report monthly sales. We'll assume that it sold 1,200 cars in the U.S. last month.

Plug-in hybrids

As always, Ford's sales breakdown lags by a day--so we won't know how many C-Max Energi and Fusion Energi plug-in hybrids it sold last month until tomorrow.

The Toyota Prius Plug-In Hybrid, rallied after several down months, selling 1,452 units. That's its best monthly number since last October, and nearing double the 786 units it sold in March of 2013.

The Ford Fusion Energi, at 899, and the C-Max Energi, at 610, both increased sales of the company's two plug-in hybrids--and followed the pattern of jointly outselling Toyota's plug-in Prius, although in this case just by a small margin.

Finally, the Honda Accord Plug-In Hybrid totaled just 18 sales for March--its lowest monthly total since February 2013, and an anomaly for a car that has sold 25 to 70 units a month for more than a year.

The high-dollar Porsche Panamera S E-Hybrid delivered 56 units, one down on the February total, making March the first month in which it was substantially outsold by the Cadillac ELR--though the numbers for both cars are still little more than rounding errors against those of the Leaf.

Low-volume and compliance cars

Mitsubishi reported that it sold 24 of its i-MiEV minicar during March, returning to its usual double digits after two months in which it sold a total of just 4 units.

In contrast, 186 sales were reported for the Smart ForTwo Electric Drive, the battery-electric two-seater--its highest monthly total ever since the latest generation went on sale last May.

Then there's the pricey Cadillac ELR range-extended electric luxury coupe, whose sales rose to 81 in its fourth month on the market, bringing total sales since December to 180 units.

The Chevrolet Spark EV had a good month too, setting a new all-time monthly sales record of 180 units in March--the highest since it went on sale last June.

The Ford Focus Electric logged 177 deliveries, its best month since last June, boosting total sales since December 2011 to a still-not-very-impressive 2,837.

And 73 Toyota RAV4 EVs were delivered in March, fewer than February's 101, but about on pace with the average number for the last six months.

Similarly, 37 Honda Fit EVs found owners, roughly in line with January and February numbers.

The Spark EV, Fit EV, and RAV4 EV are all compliance cars--vehicles built by their makers solely to meet California's zero-emission vehicle sales requirements, which will be sold only in the volume required to meet the mandate, and only in states where it applies.

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