More than 330,000 new cars were sold last month, less than 1% fewer than a year ago, outperforming industry expectations, new figures showed today.
The Society of Motor Manufacturers and Traders (SMMT) said the September plate-change saw 332,476 new cars registered, 0.8% down on the same month last year.
The society said 2011 would be a "challenging" year, with an expected full-year sales total of 1.92 million, 5% below 2010.
Paul Everitt, the SMMT's chief executive, said: "The all-important September market outperformed expectations and is less than 1% below last year at 332,476 units.
"We expected 2011 to be a challenging year and we are on track for a full year total of around 1.92 million new car registrations, 5% below 2010.
"SMMT has revised down its 2012 registrations forecast to 1.96 million units, a reflection of the continued weakness in UK domestic demand and the uncertainty across European economies.
"It is important Government acts to sustain an investment-led recovery and implements measures to encourage more private sector investment in research and development, skills, new plants and machinery."
The Ford Fiesta was the best selling model last month in the year to date, followed by the ford Focus.
September is the second largest month for new car sales after March, representing almost 17% of the annual market.
New car demand was down by 5% over the first nine months of the year, although it only dipped by 0.7% in the third quarter, today's figures showed.
The SMMT said the outlook remained "uncertain", given weakening economic growth and confidence, combined with the volatile financial markets.
The demand for fleet cars was strong last month, but private buyers slipped back, down 9.3% to 46.7% of the total, compared with 51% in the same month in 2010.
Higher diesel and alternative fuel car sales helped the average new car CO2 emissions fall by 4%.
The top 10 best-selling cars last month were the Ford Fiesta (15,647), Ford Focus (14,754), Vauxhall Corsa (14,339), VW Golf (10,628), Vauxhall Astra (10,462), VW Polo (8,607), Vauxhall Insignia (7,323), Mini (6,903), BMW 3 Series (6,352) and Nissan Qashqai (6,068).
The top five best-selling cars last month are also the top five in the year to date.