More than 2,300 examples of the iconic muscle car were snapped up over the first seven months of 2016 – almost 900 more than its closest rival, the Jaguar F-Type.
The majority of Mustangs bought so far have the range-topping 410bhp 5.0-litre V8 engine, with just 30% of customers opting for the 313bhp 2.3-litre EcoBoost engine.
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To class as a “performance” car, vehicles must boast more than 247bhp, or 250 metric horsepower. The top 10 includes the Audi TT and BMW i8, although the majority are Porsches.
The evergreen 911 was the fourth most commonly bought model between January and July, shifting more than 1,400 units, while the Cayman was fifth, with 787 examples sold.
The Boxster and the new four-cylinder 718 also featured, but only placed seventh and ninth with sales of 562 and 482 respectively.
Only one car other than the Mustang, F-Type and 911 broke the 1,000-sale barrier: the BMW 6 Series. With almost 1,450 examples sold, it was the third most popular car on the list.
Ford began selling the right-hand drive Mustang in 2015, with many buyers facing a 12-month wait due to unprecedented interest.
The original model was launched in the US more than 50 years ago as one of the first affordable American coupes, giving rise to rival models from the likes of Chevrolet and Chrysler.
The Mustang’s ascent to the top of the performance car chart comes after figures revealed that UK drivers bought more used cars in the first half of 2016 than at any other time.
Data from the Society of Motor Manufacturers and Traders (SMMT) revealed that more than 4.8 million used vehicles were sold in the first half of the year.
It is the first time that second-hand sales have broken the four-million barrier and a rise of 8% on the same period in 2015, according to the SMMT’s figures.
Ford has also begun to make serious inroads into the self-driving car market after announcing its intention to have fully autonomous vehicles rolling off production lines by 2021.