Overall for 2016 so far, the automobile industry was up over 15 percent on the same period last year.
In total, more than 17,000 cars were sold last month, with Renault once again being Portugal’s top seller.
Fellow French brand Peugeot was the second most popular, with German manufacturers Volkswagen, Mercedes-Benz and BMW completing the top five most popular new cars in the country.
Land Rover reported the biggest growth last month, with sales up more than threefold on September 2015.
In August, Mercedes-Benz surprised by coming out as the best-selling car, though it did achieve similar status in the same month in 2015, which is partially ascribed to aggressive discounts and campaigns during the summer months.
Overall, the brand from Stuttgart handed over the keys to 1,061 new proud owners, with second-placed Renault missing out on top spot after selling three fewer vehicles.
While 2016 has continued to record growth in the sales of new cars, there has been a steady slowdown since the spring, which industry analysts say is the result of yet another government tax being levied on new cars.
Latest figures from national assembly plants have meanwhile shown that vehicle production in Portugal fell by 36 percent in August compared with the same month last year.
According to industry association ACAP, just under 2,800 vehicles left the production line last month.
However, the number of heavy vehicles produced here was up by over 50 percent on 2015, and totalled 112 in August. Almost all the vehicles, or 92.5 percent, were for export, with the remainder being for domestic consumption.