The total of 82,858 cars manufactured in the UK in August is 17.3% down on last year, according to the Society of Motor Manufacturers and Traders (SMMT).
Commercial-vehicle production last month slipped even further - down 28.2% to 9,356.
But total car production for the first eight months of 2008 - at nearly 1.04 million - is still 4.5% up on the January-August 2007 figure.
SMMT chief executive Paul Everitt said: "Volatility in the global economy is adversely affecting demand for new vehicles around the world. The latest production figures reflect these challenging market conditions, but also the continued strength of UK vehicle production.
"UK-produced vehicles are exported to more than 100 separate markets around the globe. This spread of demand provides greater resilience and we expect total production to be similar to the 1.75 million produced in 2007."
In less than two weeks, the SMMT will be announcing the figures for new car sales for September this year, when the new number 58 registration plates became available.
Sales are expected to show a big fall on the September 2007 figure - showing just how deep the economic downturn is hitting the industry and consumers.
© The Press Association 2008