The total number of vehicles produced in the UK in September fell 2.8% compared to the same month in 2013 to 137,068, according to the Society for Motor Manufacturers and Traders (SMMT).
The drop came entirely from vehicles built for export, which fell 8.1% year-on-year in the period to 102,947.
In the same month, 43,121 vehicles were manufactured for domestic use, up 17.7%. As a result, 75.1% of cars produced in the UK were for export in September 2014, compared to 79.4% in September 2013.
Despite the dip, year-to-date manufacturing was still 0.6% up year-on-year by the end of September. With a total 1,132,017 cars produced in this time, the first nine months of the year were the most productive since 2008.
Mike Hawes, SMMT chief executive, said; ""It is testament to the strength of the automotive industry that it continues to break records – yielding the best year-to-date performance for six years and comfortably surpassing one million units.
"The continued investment by the sector into new models means the September figures took a slight dip as some plants underwent re-tooling but it is these same new models which will help increase production volumes in the future."