Improvements in battery, motor and inverter technology will drive the cost downwards, said Mitsuhiko Yamashita, Nissan's R&D chief.

Economies of scale in battery manufacture will make the biggest impact on electric vehicle costs, because the battery makes up to 30 to 40% of an electric vehicle's cost.

Other savings will come through a lower parts count on electric vehicles and easier design and manufacture.

"This is one of my biggest expectations that the electric vehicle will be much less complicated to engineer," said Yamashita, "because there is no emissions control and exhaust to engineer, package, test and fit and the platform is simpler."

Nissan is forging ahead with EV developments, as part of its Nissan Green Programme 2010, promising to launch an electric car in the US and Japan in 2010, Israel and Denmark in 2011 and the rest of the world in 2012.

Today's electric cars, Nissan rates as generation one, the cars launched in 2010/2011 as generation two, those between 2012 and 214 as generation three and those in 2015 as generation four.

Taking a constant cost-baseline of a conventional car in 2000 to 2015 as a comparison, Nissan believes its second generation EV will come down in cost to twice that of the conventional car.

"We have to work on governments to help us with subsidies to kick-off sales for the second-generation EV," said Yamashita.

Nissan is lobbying governments around the world for support to help EV sales. "I'd be surprised if the UK government doesn't provide some subsidies," he said.

Ideally Nissan is looking for help in offsetting around one third of the EV's cost in generation two.

A fast pace of technical and manufacturing advance is forecast to drastically reduce the cost of generation three EVs, bringing the cost to within a 30% premium.

Subsidies to reach parity with conventional-engined cars could be as little as a "few thousand pounds".

By the time generation four EVs are introduced in 2015, Nissan forecasts that their costs will be comparable with combustion-engine cars.