At the start of the year, Audi was caught testing what looked like a high-performance A1 hatchback, leading us to wonder whether the carmaker had an S1 in the works. Eleven months on and these spy shots of an S1 Sportback prototype, complete with an S-model quad exhaust system, confirm our suspicions. It appears that as the limited-edition A1 Quattro was so well received, Audi has decided to keep the potent powertrain and tone down the body in the form of a 3-door hatch and 5-door Sportback.

This prototype, pictured beside the new S3, is believed to pack a version of Audi's 2.0-liter TFSI delivering some 220-250 horsepower to all four wheels via the German automaker's trademark Quattro system. The performance-oriented premium supermini would take on the like of the John Cooper Works-spec Minis and the limited-edition Citroen DS3 Racing if and when it reaches production.