Sales of electric cars in the UK grew in October despite overall demand for vehicles shrinking as manufacturers raced to meet government targets.

Carmakers sold 29,800 electric cars during the month, up by a quarter compared with the same month last year, according to data published on Tuesday by the Society of Motor Manufacturers and Traders (SMMT), a lobby group.

That growth came despite overall October sales falling by 6% year on year. Sales of diesels were down by a fifth and petrol cars dropped by 14%.

Manufacturers must sell an increasing proportion of electric cars every year under the UK’s zero emission vehicle (ZEV) mandate. Brands have responded with a slew of new electric models, and UK electric sales reached a record high in September. Electric cars have made up 18.1% of sales so far in 2024, compared with 15.6% at the same point last year.

The industry is lobbying for the UK government to relax the mandate or fund incentives for electric car purchases. Carmakers say they are being forced into discounts that are financially unsustainable. However, analysts and climate-focused campaigners say the government should hold firm and that the ZEV mandate is working as planned.

The car-selling website Auto Trader said discounts on new electric cars on its platform hit 12.4% in October, a new record. That compared with 9% discounts across all fuel types.

Mike Hawes, the SMMT chief executive, said the ZEV mandate was weighing on overall sales.

“Fleet renewal across the market remains the quickest way to decarbonise, so diminishing overall uptake is not good news for the economy, for investment or for the environment,” he said. “EVs already work for many people and businesses, but to shift the entire market at the pace demanded requires significant intervention on incentives, infrastructure and regulation.”

The car industry across the world is struggling with falling profits. Manufacturers are asking for delays on emissions rules in the EU as well as the UK, arguing that they need to keep selling more profitable internal combustion engines in order to afford investments in electric car plants.

In the UK, bosses of BMW, Ford, Jaguar Land Rover and other big car producers wrote to the government saying the industry would miss its target.

The rules say electric cars must account for 22% of new car sales this year, or else manufacturers will face steep fines. However, there are several important loopholes, such as reducing overall emissions or selling hybrid cars that combine a smaller battery with a petrol engine.

The thinktank New Automotive has calculated that manufacturers will only have to hit 18.1% of sales – exactly the share achieved in the first 10 months. However, the industry disputes that figure.

Colin Walker, the head of transport at the Energy and Climate Intelligence Unit (ECIU), a thinktank, said: “The mandate is continuing to work as planned, driving down prices as manufacturers compete to hit their sales targets. This ‘war for motorists’ is clearly helping more and more people make the move away from paying the petrol premium that comes from owning and driving an internal combustion engine car.”