Volt made notable US gains after Detroit-based GM briefly halted production of the car this year as sales cooled after news of battery-pack fires following crash tests.
Output resumed in April with structural reinforcements for safety, as well as modifications that qualified the Volt for rebates and carpool lane access in California, the top market for rechargeable autos.
Leaf sales have dropped in the past two months as the Japan-based company has changed how it sells the car, now available in 50 US states, said Al Castignetti, vice-president of Nissan's North American sales.
"I have huge dispersion issues," said Castignetti. "In places like California dealers have pretty good inventory, but I've got states that have no Leafs, and we've got to address that."
Sales of the Leaf, which goes an average of 117km a charge, will rise to a minimum of 1000 a month by July, he said.
The Volt, which goes at least 55km on lithium-ion battery power before a petrol engine engages to top up the battery charge, remains the best-selling rechargeable car this year. Sales in May tripled to 7057, compared with 3638 plug-in Priuses and 2613 Leafs.
The four-model Prius line from Toyota City, Japan-based Toyota, which includes the plug-in version, is the biggest seller among all electric-drive autos.
Sales rose 210 per cent to 21,477 in May and 73 per cent to 107,504 for the year.
- Bloomberg
