Details with the sportiest version of the A1, called the 2011 Audi A1 1.4 TFSI have just been released.
Interestingly the range topping 2011 Audi A1 1.4 TFSI is not called the S1, so this might indicate there is something else planned for the S1 badge.
The 2011 Audi A1 1.4 TFSI uses a 1.4-litre turbocharged and supercharged unit delivering 185 HP (136 kW) and 250 Nm (184.39 lb-ft) of torque that helps the sporty mini accelerate from 0 to 100 Km/h in 6.9 seconds. 
The 2011 Audi A1 1.4 TFSI has a top speed of 227 Km/h (141 mph) and needs 5.9-litres of fuel to cover 100 Km (38.87 mpg US rating). CO2 emissions are of 139 grams per Km (223.7 g/mile).
The 2011 Audi A1 1.4 TFSI price starts at 24,250 Euro and some of the standard features include perforated front brake discs, ESP and and electronic limited slip differential 
Audi press release :
The Audi A1, the premium car among the small compacts, has been a major success following its market debut. And now Audi is presenting the new top version – the A1 1.4 TFSI (136 kW). Its taut chassis provides sporty handling, while the dual-charged 1.4 TFSI delivers 136 kW (185 hp) of power and the S tronic dual-clutch transmission comes standard. The A1 1.4 TFSI (136 kW) also impresses with groundbreaking efficiency, consuming on average just 5.9 liters of fuel per 100 km (39.87 US mpg), which corresponds to CO2 emissions of just 139 g/km (223.70 g/mile) (provisional figures).    The A1 1.4 TFSI (136 kW) has a confident appearance. The single-frame grille, the striking roof arch, the flat C-pillar, the wrap-around engine hood and luggage hatch and the tornado line show its sporty potential even when it is at a standstill.
The A1 1.4 TFSI (136 kW) has a compact, lightweight engine with four valves per cylinder. This produces an impressive 136 kW (185 hp) and 250 Nm (184.39 lb-ft) of torque. The sprint from zero to 100 km/h (62.14 mph) takes just 6.9 seconds, and the top speed is 227 km/h (141.05 mph) (performance figures are provisional).
The spontaneous response and high propulsive power, even at high speeds, are achieved thanks to its special concept – a combination of supercharger and turbocharger.
The supercharger springs into action at 1,500 rpm and in most situations is disengaged at 2,400 rpm. From 3,500 rpm at the latest, the turbocharger does all the work. Because it doesn’t have to do as much work at the low end of the rev range, the developers were able to use a large turbo and design it for high efficiency.
The 1.4 TFSI combines efficiency and dynamics. It uses on average just 5.9 liters of fuel
per 100 km (39.87 US mpg) and emits 139 g CO2 per km (223.7 g/mile) (consumption figures are provisional). These excellent numbers are the product of the FSI concept, the dual charging system and also technologies from the modular efficiency platform.
The standard seven-speed S tronic transmission directs the power of the 1.4 TFSI to the front wheels. The high-end transmission is very short and light. The seven-speed S tronic is composed of two transmission structures which are operated by two multi-plate clutches. The shifting process takes place in just a few hundredths of a second and with no detectable interruption of pulling power. The tall seventh gear reduces fuel consumption.
The McPherson construction at the front and the torsion-beam rear suspension with separate springs and dampers form the basis for agile handling.
The Audi A1 1.4 TFSI (136 kW) turns in spontaneously, takes corners quickly and stably, and accelerates out of them with sure-footed grip. The brakes have the potent performance under control. The ventilated front discs measure 288 millimeters (11.34 in) in diameter.
Another specialty that comes standard for the chassis is the ESP stabilization program with electronic limited slip differential. When the system detects an impending loss of traction at the inside wheel during fast cornering, it initiates very brief braking of that wheel.
There is a comprehensive range of equipment. The safety package comprises two front airbags, thorax/pelvic side airbags and curtain head airbags. Belt tensioners and belt force limiters plus the Audi integral headrest system round out the package. Isofix child seat anchor points in the rear are standard.
Many of the options come directly from the luxury class. These are the xenon plus headlights with LED daytime running lights, the LED tail lights, the LED interior lighting package, the high-beam assistant, the light and rain sensor, the panoramic sunroof, the convenience key with the start-stop button, two navigation systems and a 465 watt Bose surround sound system with 14 speakers. Finally, manual and automatic air conditioning systems plus heated front seats are optionally available.
The Audi A1 1.4 TFSI (136 kW) will be launched toward the end of the year at a price of 24,250 Euro. In addition to S tronic, its standard specification contains a wide range of highlights: Ambition equipment line, 17-inch wheels, S line exterior package, manual air conditioning, additional mono.pur colored interior elements, black headlining and the LED interior light package. 

Source: Audi