Usually, the summer months are less busy, according to SMMT's chief executive Mike Hawes.
"The quieter summer months are traditionally subject to fluctuation as production is paused for essential upgrades, and August's strong growth wasn't unexpected given the 22.1 percent fall in the same month last year when the 2014 holiday period fell," Hawes said in a press release.
Year-to-date, output has increased by 1.6 percent to 1,011,127 in 2015 from 994,951 in 2014.
"With an overall increase of 1.6 percent so far in 2015 and the strongest year-to-date performance since 2008, the industry is in a good position," Hawes added.
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This was backed up by Ian Fletcher, an autos analyst with IHS, who told CNBC he expects U.K. production to reach 1.55 million units for the year.
"An even more significant uplift will be recorded during the next couple of years when output will peak at 1.78 million units during 2017, underpinned by new models and investment that has been made by original equipment manufacturers," he told CNBC via email.
The number of cars made for the U.K. market has increased by 11 percent from 213,772 to 237,438 cars.
However, the number of cars for export has dipped by one percent from 781,179 down to 773,689. The slight fall is down to a fall-off in demand for premium models in key markets such as China and Russia, Thomas Glendinning, an autos analyst with BMI Research told CNBC by email.
"On the whole this is not a reflection of a more widespread issue with export markets, as we are seeing positive growth in the rest of Europe - a major destination for U.K. exports," he added.