New car sales accelerated ahead again last month, rising 13.5% compared with May last year, it was announced today.
This was the 11th successive month that registrations of new vehicles have risen.
But the Society of Motor Manufacturers and Traders (SMMT), which released today's figures said sales - boosted last year by the now-ceased car scrappage scheme - could dip slightly this year compared with 2009.
SMMT chief executive Paul Everitt said: "May was another good month for the UK new car market, although we expect the coming months to be extremely challenging.
"It is essential that the upcoming emergency Budget promotes consumer and business confidence to maintain economic recovery."
Last month saw 153,095 new cars registered in the UK compared with 134,858 in May 2009 - the first month in which the sales-boosting scrappage scheme was introduced.
Sales for the first month of this year, at 913,436, are up 22% on the January-May 2009 total.
But the SMMT said a "modest decline" in registrations was expected in the second half of this year.
The scrappage scheme closed to new orders in March this year but a final few scrappage registrations were made last month.
Sales of alternatively-fuelled vehicles rose almost 200% last month and accounted for 1.1% of the market. Demand for diesel cars rose dramatically last month with the diesel share of the market reaching a near-record 46.9%.
The Ford Fiesta was knocked off the top of the best-selling models' table for the first time this year, being replaced by another Ford car, the Focus.
These were the top 10 best-sellers in May 2010:
1. Ford Focus
2. Vauxhall Astra
3. Ford Fiesta
4. Vauxhall Corsa
5. Volkswagen Golf
6. BMW 3 Series
7. Volkswagen Polo
9. Nissan Qashqai
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