Car production slammed into reverse last month amid falling demand in the UK for new vehicles, a report shows.
There was a 14.2% drop in production for the home market, with 31,421 cars built in September for UK buyers, compared with 36,607 in the same month a year ago.
Total car production last month was 4.1% down at 153,224, with exports falling by 1.1%, the Society of Motor Manufacturers and Traders (SMMT) said.
Just under 1.26 million cars were built in the first nine months of the year, 2.2% fewer than the same period in 2016.
Mike Hawes, chief executive of the SMMT, said: "With UK car manufacturing falling for a fifth month this year, it's clear that declining consumer and business confidence is affecting domestic demand and hence production volumes.
"Uncertainty regarding the national air quality plans also didn't help the domestic market for diesel cars, despite the fact that these new vehicles will face no extra charges or restrictions across the UK.
"Brexit is the greatest challenge of our times and yet we still don't have any clarity on what our future relationship with our biggest trading partner will look like, nor detail of the transitional deal being sought.
"Leaving the EU with no deal would be the worst outcome for our sector so we urge government to deliver on its commitments and safeguard the competitiveness of the industry."