Diesel car sales in July plummeted by 20.1% compared with the same month last year, helping to depress overall sales in the UK new car market by 9.3% for the month, according to figures published by the Society of Motor Manufacturers and Traders (SMMT).

A total of 161,997 new cars were registered in the month, to record the fourth consecutive monthly fall. Petrol car sales were down 3% from 86,550 to 83,969, while diesel sales sell from 86,594 to 69,157.

Demand for alternatively fuelled vehicles (AFVs) soared 64.9% as they took a new record 5.5% market share in July, with 8,871 new units sold. Nearly 70,000 new AFVs have joined UK roads this year.

Demand was down across business, fleet and private buyers – with corresponding falls of -23.8%, -10.1% and -6.8%.

The only two vehicle segments to enjoy growth were dual purpose and specialist sports cars, with increases of 7.3% and 10.3% respectively.

SMMT chief executive Mike Hawes said: “The fall in consumer and business confidence is having a knock-on effect on demand in the new car market and government must act quickly to provide concrete plans regarding Brexit.

“While it’s encouraging to see record achievements for alternatively fuelled vehicles, consumers considering other fuel types will have undoubtedly been affected by the uncertainty surrounding the government’s clean air plans.

“It is important to remember that there are no plans to charge drivers using the latest Euro 6 models and no proposed bans for conventional petrol and diesel vehicles for some 23 years.

“The lower demand in recent months will inevitably mean competition from manufacturers will intensify and it will be a good opportunity for consumers to get a great deal on their next car, with many exciting new models launched in the coming months.”

Sue Robinson, director of the National Franchised Dealers Association (NFDA), commented: “Following recent government announcements and given the decline in petrol and diesel registrations, clear messages are needed to not cause further confusion to car buyers. It is vital that modern Euro 6 diesel cars are not compared with older diesel vehicles, information surrounding diesel must be clarified for the consumer.

“The growth in alternative fuel vehicles sales is encouraging but consumers need continued guidance and support to ensure a stable and gradual shift which will drive the market in the long term. In particular, the government should invest in charging infrastructure.”