London, England (CNN) -- Major car manufacturers are poised to launch their electric vehicles and expectations are so high Nissan says it has closed its U.S. waiting list with 20,000 pre-orders.
It's no wonder people are excited, with promises of zero carbon emissions, running costs less than a quarter of that of conventional cars and government incentives in some countries including subsidies, exemption from road tax and free parking.
So are these silent machines about to take over the world?
Well, not quite. Despite their impressive claims, even their most ardent supporters admit electric cars aren't about to replace conventional vehicles.
Michael Lock, chief marketing officer at THINK, manufacturer of the world's best-selling electric car so far, told CNN: "Some manufacturers are marketing electric cars in the same way as conventional cars, but that creates confusion.
"They are a niche, and people need to understand their function. They are basically for city driving or commuting into a city, where the round trip is 60 to 80 miles."
Electric cars can go around 70 miles between charges and have a top speed of around 70 miles per hour.
Lock said: "They are not at the stage where they could replace the primary car for many people.
"The range needs to double or treble and the cost needs to come down before they can be seen as replacing petrol or diesel cars.
"With anticipated advances in technology, we believe electric vehicles could be taking 20 to 25 percent of the total car market by 2020."
This target is a long way off at the moment. The THINK City car has sold 2,500 models so far, mostly in Norway where the company is based. It has recently expanded to other European countries, with more to follow soon.
THINK will sell its first cars in the United States in December, starting with 300 cars bound for Indiana.
The major car manufacturers are just breaking into the market. Mitsubishi launched its i-MiEV in Japan in April and will break into the UK in January next year. Nissan launches its Leaf in the United States in December, having received 20,000 pre-orders.
The cars don't come cheap. The THINK City costs around €30,000 ($42,000), although the price in each country depends on government incentives. The UK government, for example, is offering a £5,000 ($7,860) subsidy. In the United States, where cars are cheaper, the Nissan Leaf costs $25,280 after federal tax savings.
The running costs, however, are low. Christina Fell, program manager of CABLED, an electric car trial in the UK, estimated most electric car fuel costs are between a fifth and a quarter of those of conventional cars.
Tim Armitage, of the engineering firm Arup, which is leading the CABLED trial, told CNN, "We are still very early in the electric car era. Most manufacturers are still dipping their toes in the water.
"I don't think in my lifetime or my children's lifetime electric cars will completely replace petrol or diesel cars, because they are also becoming more efficient.
"There will be a mix on the roads and people will think about what's best for the type of journeys they make."
CABLED is the largest of eight year-long low-carbon car trial schemes in the UK where householders lease vehicles for a year and data from their usage is recorded.
Initial results of the trial suggest that usage of electric cars is similar to that of conventional cars and that their range is sufficient for most participants' everyday journeys.
Although electric cars themselves have zero emissions, their environmental benefit depends on how the electricity that powers them is generated.
In the UK, a Department for Transport report estimated electric cars have 40 percent less carbon and greenhouse gas emissions than conventional vehicles over their lifetime. The report predicts this will improve further as electricity generation becomes greener.
Lock told CNN that the growth of the electric car market depends on the speed at which governments build the infrastructure for charging them in city centers, as well as the price, range and performance of the cars themselves.
He said the most advanced cities so far were Oslo, Vienna and Amsterdam, although they could all be overtaken by London if proposed measures go ahead.
London Mayor Boris Johnson announced he wants 100,000 electric cars on the city's streets as soon as possible, up from 1,700 currently. He has promised 25,000 charging stations across the British capital by 2015.
China's state news agency Xinhua this month quoted Minister of Science and Technology Wan Gang predicting the country would produce one million electric vehicles a year by 2020 to help combat pollution in cities.