Ed Miliband’s new net zero targets are not credible, carmakers have warned.

The Society of Motor Manufacturers and Traders (SMMT) said the Energy Secretary’s latest so-called carbon budget implied electric vehicle (EV) sales need to triple in just three years.

This was “highly unlikely” on current trends, the industry lobby group said, even though demand has risen significantly.

New figures published on Thursday showed that 24pc of new car sales were electric in the first five months of this year. However, the proportion remains well below the government target of 33pc for 2026.

Mr Miliband’s latest carbon budget is based on modelling that assumes 95pc of sales will be electric by 2030. The SMMT said that “if such targets are to be credible, then equally ambitious fiscal and investment support would be essential”.

Mike Hawes, the SMMT’s chief executive, said the figure was not realistic given current demand.

He said: “The EV transition is progressing, but consumer uptake still lags behind even today’s targets, let alone the ambition set out in the latest carbon budget.

“While industry shares the long-term ambition, the pathway to net zero must be credible. It cannot come at the cost of lost competitiveness and deindustrialisation.

“A review of the transition is now urgent to ensure we have a sustainable path to road transport decarbonisation.”

The seventh carbon budget, backed by Mr Miliband on Tuesday, sets a target to reduce Britain’s total emissions by 87pc, compared with 1990 levels, by 2040. It is based on modelling by the independent Climate Change Committee (CCC).

A Whitehall source claimed the carbon budget figure endorsed by Mr Miliband did not necessarily include the EV sales target as the CCC’s modelling looked at just one possible pathway to hitting the target.

However, the overall budget is legally binding, meaning the emission savings would have to be found elsewhere if EV sales do not accelerate.

That could potentially include a bigger rollout of heat pumps, stricter curbs on flying or eating meat, a faster transition to green energy or greater use of technologies such as carbon capture and storage.

A spokesman for Mr Miliband’s department could not say on Thursday how his intended pathway would differ from the CCC’s recommendations. The Government has said it will publish more detailed proposals “as soon as is reasonably practical” after Parliament formally approves the carbon budget.

Figures published by the SMMT on Thursday showed the market share of EVs was 27pc in May, up from about 22pc a year earlier. Some 43,900 electric cars were sold during the month, up from 32,700 last year, an annual increase of 34pc.

The SMMT said the uplift was thanks to “expanding model choice and sustained competition”, including ongoing heavy discounting by manufacturers.

By comparison, petrol and diesel car sales fell by 7pc and 2pc respectively. Sales of plug-in hybrids – which have surged in popularity in recent years – rose 24pc to about 22,200.

Sales of EVs have been boosted in recent months by a surge in petrol prices following the outbreak of the Iran war.

Mr Miliband insisted on Tuesday that pressing ahead with his clean power plan was the only way to shield the UK from such economic shocks in future.

He said: “Some people want to stick their heads in the sand and let our children face the consequences of climate breakdown but this government believes in the timeless British value of protecting our country for generations to come.”

Tanya Sinclair, chief executive of lobby group Electric Vehicles UK, said: “Instead of scaremongering about readiness, let’s all ensure supply, charging and policy keep pace with a market that’s going electric at pace.”

Under the electric vehicle mandate rules, car companies are given various “flexibilities” that allow them to temporarily undershoot the targets or achieve them through selling more hybrid vehicles instead.

New Automotive, a consultancy, has estimated that this year’s “real target” – when such flexibilities are taken into account – is 24.6pc.

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