Sales of new diesel cars have plummeted, according to the latest figures released by the Society of Motor Manufacturers and Traders (SMMT).

New diesel car sales were 81,489 in May, 20% down on the corresponding month last year when 101,844 were sold. The market share of diesel cars also declined from 50% in May 2016 to 43.7% last month.

The plunge in diesel sales also pushed the overall market into decline with total new car registrations at 186,265, down 8.5% on the same month last year.

Sales of petrol cars were marginally up at 96,518, an increase of 0.4%, and now comprise 51.8% of the market.

Although it dipped slightly in the previous month, the market for alternatively fuelled vehicles (AFVs) bounced back in May to continue the upward trend seen in the first quarter and take a new record market share of 4.4%. More than 8,000 AFVs were registered in the month, representing an increase of 46.7% on the same month last year. Almost 50,000 new AFVs have joined Britain’s roads so far this year.

SMMT chief executive Mike Hawes said: “We expected demand in the new car market to remain negative in May due to the pull-forward to March – which was an all-time record month – resulting from VED reform. Added to this, the general election was always likely to give many pause for thought and affect purchasing patterns in the short term.

“Although demand has fallen, it’s important to remember that the market remains at a very high level and, with a raft of new models packed with the latest low emission and connected technology coming to market this summer, we expect the market to remain strong over the year.”

“New passenger car registrations declined in May but year to date the overall new car market remains strong. The General Election may have a short-term impact on consumer confidence, but franchised car retailers continue to see solid footfall through the dealerships and in the medium and long term consumer spending is expected to remain stable,” said Sue Robinson, director of the National Franchised Dealers Association (NFDA), which represents franchised car and commercial vehicle dealers in the UK.

She added: “The growing importance of low emission vehicles is reflected in the strong performance of AFVs in May. However, there must be continued and coordinated support from government and industry to encourage the uptake of these vehicles, which have now reached a record market share, to ensure that the segment remains strong.

“In a period of change it will be interesting to see what the upcoming months have in store. Positively, the overall 2017 new car market seems set to stay at historically high levels.”