The Society of Motor Manufacturers and Traders (SMMT) has blamed new emissions testing requirements for a 20.5% fall in sales of new cars in September.

A total of 338,834 vehicles were registered in the month, down around 87,000 on September last year, with the new WLTP (Worldwide harmonized Light vehicles Test Procedure) affecting supply and distorting the market, according to the SMMT.

Registrations of diesel cars were worst hit, with sales down 42.5% compared with September 2017, and the market share for diesel was 29%.

Petrol car sales were also down 6.7% while hybrids and plug-in electrics were up 3.9%.

SMMT chief executive Mike Hawes said: “With the industry given barely a year to reapprove the entire European model line-up, it’s no surprise that we’ve seen bottlenecks and a squeeze on supply. These are exceptional circumstances with similar declines seen in other major European markets. The good news is that, as backlogs ease, consumers and businesses can look forward to a raft of exciting high-tech cars and a market keen to recover lost momentum.”

Sue Robinson, director of the National Franchised Dealers Association (NFDA), said: “Consumer footfall has remained fairly robust although a proportion of motorists feel unsure about which car to buy due to the lack of clarity surrounding a number of key policy areas. We encourage consumers to talk to their local franchised dealership to obtain a better understanding of the current market offering.

“We expect the market to remain steadier through the remainder of the year as stock supply improves. The used market is likely to continue to perform well.”