You do not have to be a cynic to know that utopias are just whopping big pies in the sky.

The one currently being hawked by our masters is the brave new world of the electric car, a place in which there are no noxious emissions from petrol and diesel engines, and where the air in city centres is as clean and as sweet as an exclusive Alpine resort.

This pure air, free of nasty carcinogens and toxic particles, will save the lives of many of the estimated 40,000 people in the UK alone who are killed by air pollution each year.

Like all utopias, it sounds seductive — so wonderful, in fact, that cities and even entire countries have pledged to ban all petrol and diesel vehicles within the next two decades.

Westminster Electric Car Juice Point where electric vehicles get their batteries charged

Last month, Oxford City Council announced it would start ridding itself of petrol and diesel vehicles from some streets by 2020, with a view to a total ban by 2035.

In France, President Emmanuel Macron’s government, in a typical display of Gallic hubris, has declared an ‘end to the sale of petrol and diesel cars by 2040’, which would be a ‘veritable revolution’ according to their ecology minister. Holland is planning a similar move in just eight years’ time, and even India is considering a ban by 2035.

The British Government, meanwhile, has announced an ‘aspiration’ for all new vehicles to be electric or ultra-low emission by 2040. Although this is somewhat less ambitious than other countries, ministers are still sending out a clear signal — it’s all go for the electric car.

But not so fast. It’s time for a reality check about electric cars, and to realise that they can be every bit as polluting as their petrol and diesel forebears.

Research recently published by the Trancik Lab of the highly esteemed Massachusetts Institute of Technology (MIT) could wipe the smug expressions off thousands of electric car drivers’ faces.

The boffins at the Trancik Lab have shown that an electric Tesla Model S P100D saloon produces more carbon dioxide, at 226g per kilometre, than a petrol-driven run-around such as the Mitsubishi Mirage, which is responsible for just 192g/km.

Tesla Model S P100D saloon produces carbon dioxide at 226g per kilometre, according to Massachusetts Institute of Technology

And unfortunately for Tesla drivers who would rev their engines in fury and declare the research an anomaly, the MIT finding backs up that of the Norwegian University of Science and Technology, which last year declared: ‘Larger electric vehicles can have higher life-cycle greenhouse gas emissions than smaller conventional vehicles.’

So what’s going on here? Surely electric vehicles are necessarily greener. Since they don’t have exhaust pipes, what on earth can be causing the pollution?

Before we come to the answer, one salient point needs to be established — electric cars are indeed greener than petrol and diesel cars of the same size. If, for example, that Tesla saloon is compared with a large, petrol-driven BMW 750i saloon, its figure of 226g of CO2 compares well to the 385g that the BMW emits every kilometre.

Yet as we shall see, that is no reason for electric car drivers to polish their halos just yet.

First, there is the obvious point that the energy that charges the batteries of an electric car has to come from somewhere. Unless you have your own private power station that runs on renewable energy, the chances are that you will be using the National Grid to charge your car overnight.

And where does the National Grid’s electricity come from? According to the latest figures in the Digest of UK Energy Statistics, 51 per cent of it comes from power stations that burn fossil fuels, such as gas and coal. Nuclear power — much loathed by many greens — is responsible for 21 per cent of your car’s power, while just under a quarter of the power comes from renewable sources.

The research found that at petrol-driven run-around such as the Mitsubishi Mirage, which is responsible for just 192g/km

So yes, while having an electric car certainly reduces roadside emissions, the increased demand required to charge electric vehicles means more fossil fuels being burned at power stations, which of course worldwide pump millions of tons of pollutants into the atmosphere.

Second, because under Government policy all electric cars are officially classified as ‘zero emissions’, many owners are under the impression that their cars can be big, and yet miraculously have no environmental consequences. Whereas, as we have seen, the research states categorically that large electric cars can be more polluting that small petrol ones.

Drivers are also after cars with a long range — the distance they can travel before having to be charged up again. The average electric vehicle today offers a range of around 150 miles, according to data provider EV Volumes. Tesla claims that its Model S can do up to 424 miles and other manufacturers are aiming to get their range up to around 400 miles by 2022.

But the point is that big cars with long ranges need batteries with lots of power, and the more power they use, the more pollution they cause. If electric car drivers are really as green as they think they are, then they should ensure their cars are smaller. As Nico Meilhan, a car analyst and energy expert, explained to the Financial Times: ‘If we really cared about CO2, we’d reduce car size and weight.’

The third part of the problem lies in those batteries. Mining the huge amounts of nickel, cobalt and lithium used in their manufacture comes at an environmental cost. As Mr Meilhan says: ‘If you switch from oil to cobalt and lithium, you have not addressed any problem. You have just switched your problem.’

A 2009 study revealed that nickel was the eighth worst metal to mine and process in terms of global warming and pollution. Villagers who live next to the Cerro Matoso nickel mine in Colombia, for example, have reported higher rates of respiratory diseases and birth defects.

Producing lithium also has an environmental cost, as rocks need to be crushed, often in Australia, and then shipped to China to be processed. The lithium extracted from South American deserts results in one ton of carbon dioxide for every ton of lithium carbonate produced.

A large, petrol-driven BMW 750i saloon consumes 226g of CO2 which compares well to electric cars of the same size

And then of course there is the problem of what happens to the batteries when they reach the end of their lives. It is thought that 11 million tons of old lithium-ion batteries will be thrown away over the next 12 years, of which only 5 per cent will be recycled.

The fourth problem with electric cars is that their manufacture can often be just as environmentally damaging as producing petrol or diesel-driven cars. After all, the steel, glass, plastics and fabrics used are much of a muchness.

Very few electric cars are built with a proper sensitivity to the environment. One that does do well is the BMW i3, the seats of which are made from recycled bottles, and whose carbon fibre body is produced in a factory that runs purely on hydroelectricity.

The fifth and final part of the problem is the notion that, because electric cars do not have any exhaust, they truly are ‘zero emissions’ when being driven.

Unfortunately, this is nonsense. Like all other cars, electric vehicles produce pollution from tyre and brake dust. According to a paper produced by the European Commission, a staggering half of all particulate matter in the air comes from these sources.

‘While governments don’t currently pay much attention to particulate matter, it is in fact highly polluting, with strong links to cardiopulmonary toxicity,’ the Government’s top adviser, Professor Frank Kelly, wrote recently in The Guardian.

Professor Kelly, who chairs the Committee On The Medical Effects Of Air Pollutants, also stated that the Government’s plan to phase out petrol and diesel cars did not go far enough. ‘Our cities need fewer cars, not just cleaner cars,’ he wrote.

The answer, then, appears to be obvious. If we really do want that utopia, then we should just get rid of cars, electric or otherwise, and get on our bikes.

Now that really is pie in the sky.