New car registrations in the UK experienced a decline in May, falling 8.5% year-on-year to 186,265 cars, according to the Society of Motor Manufacturers and Traders (SMMT).

The decline was driven largely by falling diesel sales, which experienced a 20% decline, slipping to 81,489 cars from the 101,844 diesel cars registered in May 2016. The share of diesel cars fell to 43.7% from 50% a year ago.

Petrol vehicles remained largely static, falling just 0.4% over the same period, while sales of alternatively fuelled vehicles (AFVs) rose by 46.7%, reaching 4.4% of the market, compared to 2.8% the year prior.

By segment, private vehicle sales experienced a marked decline of 14%, with 76,544 registrations in May, down over 13,000 from May 2016. Fleet sales fell by 5.3% to 109,489 cars, and business sales rose 20.1% 6,054 cars.

The Ford Fiesta was the best-selling car in May 2017, with 7,617 registrations, outselling the second-place Volkswagen Golf by over 2,000 cars.

In the year to date in May, registrations were largely static, with a 0.6% decline leading to 1,164,870 registrations over the period.

Chris Bosworth, director of strategy at Close Brothers Motor Finance, said the political situation and the rise in Vehicle Excise Duty (VED) was responsible for the decline, and expected it to continue.

Bosworth said: “The unsettled political landscape and rising inflation has impacted consumer spending, and the recent new vehicle tax rate is certainly impacting new car growth.

“Following the general election and as we enter the Brexit discussions it’s likely we’ll continue to see this pattern continue.

Mike Hawes, SMMT chief executive, said the results were in line with the SMMT’s expectations and that over the year, the SMMT expected the market to be strong.

Hawes said: “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 paced with the latest low emission and connected technology coming to market this summer, we expect the market to remain strong over the year.”

Sue Robinson, director of the NFDA, urged the government to encourage the adoption of AFVs. She said: “There just be continued and coordinated support from government and industry to encourage the uptake of these [alternatively-fuelled] vehicles, which have now reached a record market share, to ensure that the segment remains strong.”