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Not since the heady Auto Union days of the mid 1930's has Audi boasted a supercharged car. Then it was racer.
Today it's a high-performance sedan, the S4 launched in Australia this week. The 3.0 litre V6 supercharged engine replaces a 4.2 litre V8 in the previous S4, released here in November 2005. Not only is the V6 more powerful with 440 Nm of torque, but is leaves the V8 for dead in the economy stakes, using 24 per cent less fuel, a saving of three litres/100 kms. It's also faster to 100 km/h at 5.3 seconds half a second quicker than the V8. While the V6 has more bang, S4 fans will miss the V8 burble. The V6 puts out a hiss and a small `pop' as the seven speed S-Tronic dual clutch shifter struts its stuff in what seems milliseconds between gearshifts.
The V6 produces 245 kW of power compared to the V8's 253 kW. It has direct fuel injection and mechanical supercharging using an Eaton Corporation Roots-style system ... much the same as the Auto Union racers. However, Eaton have been able to develop a system that is more fuel efficient than early Roots systems.
“Extensive testing on the big V6 has proven the superiority of mechanical charging,” said an Audi spokesman. “In conjunction with direct injection is it far superior to twin turbochargers, both in terms of packaging and of starting performance and responsiveness.”
The compressor fits inside the 90 degree V of the cylinder banks, in place of an intake manifold. Maximum torque hits at 2500 rpm and goes right through to 4850 rpm. Power is put to the ground via Audi's all wheel drive quattro. While the change in engine is the most notable alteration to the S4, it is not the only improvement. The new S4 features a five-link front axle and self-tracking trapezoidal-link rear axle made almost entirely of aluminium. It now has low mounted steering gear that sends the steering force to the wheels without any lag time, giving the driver a more precise road feel for the car.
Stiffer shock absorbers put the car 20mm closer to the ground. The S4 has also gone higher-tech with Audi's select driving dynamics system. This allows the driver to choose between `comfort' `auto; and `dynamic' settings that operate on the throttle response, shift points for the S-Tronic, and steering. It's a press button system. It also comes with optional extras for those who take their motoring seriously.
Buyers can choose between adaptive dampers or a sport differential, adaptive control for the shock absorbers and with dynamic steering. The system reduces the load on the ESP in high speed cornering and stabilises the car through lightning-fast steering interventions. This is not for you average punter as it comes into play when the car is at it's handling limits. Audi claim the active sports differential elevates the road dynamics of the quattro car to a new level. Like a centre differential lock which distributes torque between the front and rear wheels, the active sport lock operates laterally on the rear wheels. It can divert virtually all torque to just one of the wheels, pushing it in the same direction as the steering wheel. This helps the driver send the car in the direction he wants.
The result is quicker turning into corners and the benefit of longer-lasting directional stability. Visually, the S4 is impressive. Audi have continued with the now-familiar Xenon plus headlights with LED daytime running lights and rear LED lights. These give the car a distinctive daytime appearance. S4 is finished with 18 inch alloy wheels, sill panels, subtle rear spoiler and a not-so-subtle quadruple exhaust system, that looks like it should belong to a V8. What is somewhat bemusing is the V6 T badge on the front mudguards.
T for Supercharger? Surely they mean T for Turbo? Audi has taken the stand that `T' no longer merely stands for `turbo' but for the concept of supercharging in general. The interior continues the sporty flavour with sports seats featuring electric lumbar support and pull-out thigh support, instrument panel with grey dials and white needles and multi-function steering wheel along with `S' emblems.
FIRST STEER
Firstly, we miss the burble. V8 burble. The unmistakable sound of a V8 with the pedal to the metal. We also wonder if S4 buyers will also mourn the loss of the V8. If you can afford an S4, then the extra hit in the wallet of three litres every 100 kilometres for the V8, will not matter one hoot. Then again, that's a comment that is not politically correct for these times.
The V6 is a highly responsive engine that actually develops an engine note not dissimilar to a straight six engine. That's good. Mated with the seven speed S-Tronic the S4 is a potent package with Audi's usual understated appearance. It points beautifully, although we did not get to drive the cars with the sport differential. The ride is excellent for a car with this degree of sporting prowess. On uneven tar is is composed and river feedback excellent. Passing at speed is a sensation with the S4 rocketing from 80 km/h to 120 km/h in a mere 4.4 seconds. Out, passed and back in in a blink of an eye. We like it.
PRICING
Audi S4 3.0 Supercharged rrp $118,900
Vast options array including Audi drive select with adaptive dampers $2600 and Audi drive select with full handling package including sports differential $6700.
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