Declining demand from Europe put the brake on UK car production last month.
There were 128,192 cars made in the UK in September 2012 - a 5.8% fall on the September 2011 figure, the Society of Motor Manufacturers and Traders (SMMT) said.
Commercial vehicle (CV) production fell even more last month - dipping 20.2% to 9,607.
Engine production in September 2012 was also down - slipping 12.8% to 213,052.
Despite the September fall, car production for the year so far, at 1.08 million, is up 10.2% compared with the January-September 2012 total.
CV production in the first nine months of this year is down 7.5% at 82,315, while engine production has fallen 0.4% to just over 1.88 million.
SMMT chief executive Paul Everitt said: "Declining demand for cars and vans across the major European markets impacted UK vehicle and engine production in September.
"Total UK vehicle manufacturing in the year so far has increased, but monthly output fell in September."
He went on: "The strong demand for UK products outside Europe and the investment committed by major vehicle manufacturers will secure future growth, although the coming months will be challenging for companies at all levels in the supply chain.
"European governments must focus on securing financial stability and economic growth or they risk long-term damage to key industries."
