Audi’s S4 performance sedan will debut at the Paris auto show in October featuring an enviable blend of performance and economy.Though many predicted the S4 would feature a ‘twin-charged’ engine, Audi have settled on a supercharged V6 with direct fuel injection. Displacing only 3-litres, the engine attempts to satisfy both performance demands from keen driving customers and subscribe to environmental emissions controls.Intercooled quick sixProducing 245kW and 440Nm, the 90-degree V6 engine features a small compressor, operated by two four-vane rotary pistons which counter-rotate inside the compressor at speeds of up to 23 000r/min. Two charge-air coolers are integrated into the housing and connected to a separate coolant circuit.The net result is an engine which can power the S4 from 0-100km in 5.1 seconds and retains claimed combined cycle efficiency of 9.7l/100km. Power is channelled via Audi’s renowned quattro drive system and sports seven gears thanks Audi’s latest dual-clutch S tronic gearbox - featuring a ratio spread of 8.0:1.Active differential makes a big differenceNo Audi product with a S prefix could do justice to the performance arm of Ingolstadt without a sophisticated all-wheel drive system. In normal commuting the all-wheel drive system sends torque in a 40/60 split to the four drive wheels in a rear-wheel drive bias. Drivers who wish to push on a bit can customize the new active sport differential setting. The active sport differential is a new type of rear-axle differential featuring a superposition gear added to both the left and right sides of the classic differential; it rotates 10% faster than the wheel’s drive shaft. If steering angle and throttle applications are too extreme and break traction on the inside wheel of the cornering line, the differential immediately applies power to the outside wheel – which naturally has better traction – and ensures optimal traction and drive out of the corner. Audi claims its sport differential is just as effective when the engine is driving the wheels as it is on the overrun or when the car is coasting freely. Other dynamic enhancers include adaptive ride (optional) and Audi’s drive select system already seen locally on some A4 models. Suspending the latest S4 is a five-link front axle and self-tracking trapezoidal-link rear axle made almost entirely of aluminium. The low-mounted steering gear transmits steering forces to the wheels without any lag time and gives the driver a precise and sensitive road feel.As with the rest of the A4 range the S4 has seen its front differential positioned ahead of the clutch, enabling the engine to move 154mm forwards compared with the predecessor, improving interior space and axle loads. On right hand drive models it has ruined the pedal positioning though…. S models received stiffer axle bearings too and have seen a 20mm ride height reduction. Behind the standard 18-inch mags hide black-painted callipers with S4 logos at the front.LED lights everywhereExterior design elements include special aprons, aluminium-look exterior mirrors, side rocker panels, a restrained rear spoiler at the requisite quadruple exhaust system. The xenon plus headlights with daytime running lights add a further distinctive touch which are becoming a bit staid now, yet blend with the oversized front grille as an Audi design cue. Interior S range appointments are sports seats featuring electric lumbar supports and pull-out thigh supports, gray dials with white needles and a host of S4 emblems. The interior is in black, with brushed aluminium inlays. Carbon and birch wood inlays are also available, as are stainless steel mesh inlays.Audi will begin delivery of its new S models in Europe during March next year after the car debuts at the Paris motor show from 2-19 October.