BY LUCIANO PAOLINO | 22nd May 2009
After two generations of V8 power, Audi has switched back to a boosted V6 for the latest S4 which arrives with a sticker price of $118,900.
For many years, the turbocharger has been Audi’s forced induction method of choice, but this time, Audi has selected a supercharger.
This might come as a surprise, but it is the first time Audi has used a supercharger since the Auto Union racers of the mid 1930s.
The company said it investigated fitting twin turbos to its V6, but found it got a better result with a single supercharger.
The new direct-injection 3.0-litre S4 engine pumps out 245kW at 5500rpm and 440Nm of torque from 2500rpm to 4850rpm.
It replaces a 4.2-litre naturally aspirated V8 which was good for 253kW and 410Nm.
The S5 coupe, which is based of the current A4 platform and costs $138,600, will retain its 4.2-litre V8 for now.
The new V6 uses a single Eaton supercharger nestled between the two cylinder banks, built into the intake manifold.
It is a Roots type supercharger with a maximum boost pressure of 0.8 bar.
Strangely, the new supercharged unit is still referred to as a TFSI, the first letter of which used to refer to the engine’s turbo.
Adding to the confusion, Audi has also placed a badge on the front guards of the S4 reading V6 T, which a reasonable person could take to indicate that it is a V6 turbo.
The new S4 is only available with an automatic transmission. The good news is that instead of running a traditional torque-converter type gearbox, Audi has slotted in a quick-shifting seven-speed dual-clutch DSG, or in Audi terms, S-tronic – the first in an A4.
The S4 uses the quattro all-wheel-drive system with a Torsen centre differential with a default setting that sends 60 per cent of power to the rear and 40 per cent to the front.
The new S4 is capable of surging from 0-100km/h in just 5.3 seconds, which is 0.3 seconds faster than the previous car.
While it probably doesn’t matter much to people rich enough to buy this kind of car, the new six-cylinder S4 uses far less fuel than the V8 version it replaces.
The new car has an average fuel consumption figure of 9.4 litres per 100km which is impressive given this is a seriously fast car.
It looks even better when you consider it uses 24 per cent less fuel than the old V8.
Previous generation S4s were Audi’s answer to the BMW M3 and Mercedes-Benz C AMG. Interestingly, both of those cars used to run six-cylinder engines, while the Audi had an eight.
Then Audi introduced the screamer RS4 which made the S4 look a bit soft, and BMW decided to bolt a 309kW V8 under the bonnet of the M3 and Mercedes pulled out its big-daddy 6.2-litre V8 (336kW) for its mean C-class.
So even though the RS4 has been put to pasture, the S4 is no rival to the M3 and C63, which are both more powerful and have a much harder edge.
Audi refers to the S4 as an everyday sportscar.
The new S4 is based on the new A4 sedan, which represented an important step forward for the mid-size machine from a handling perspective.
Previously, the A4’s steering rack was mounted on the car’s body, which contributed to a slightly detached feel. Vibrations could also often be felt through the steering wheel when the car cornered on uneven surfaces.
Audi engineers aimed to iron out these wrinkles by re-positioning the steering rack forward of the front axle. They also shifted it down closer to the road and mounted it on to the subframe rather than the body.
Like the regular A4, the S4 runs double wishbone front suspension and a trapezoidal multi-link set up at the rear.
It runs sports springs which means car sits 20mm lower than the standard model.
Adaptive damping, which uses a special valve rather than the magnetic charge system available on some other Audis, is also available as an option for $2600.
The S4 comes standard with 18-inch alloy wheels, but optional 19s are available for $2600.
The brakes have been upgraded to cater for the high output of the engine. The S4 runs ventilated discs all round, which measure 345mm at the front and 330mm at the rear.
Audi says the brake pad surface area has been increased by 25 per cent at the front and 60 per cent at the rear.
While Audi’s quattro AWD system is standard with the new S4, the company has introduced a new optional system that offers a further improvement. Called Sport Differential, it is basically a rear differential that constantly manages the power flow between the rear wheels to help with cornering.
This kind of active system has already been introduced on cars like the Mitsubishi Lancer Evolution and the BMW X6.
The idea is that when a car is cornering power can be directed to the outer rear wheel to help the vehicle round the bend. Audi claims that this feature stops the nose from pushing on through a bend, eliminating understeer.
Sport Differential is not available as a stand-alone option, but can be bought in a package with adaptive damping and dynamic steering for $6700.
While there is a long list of expensive options, including metallic paint for $1695, the S4 comes with a lot of standard features you would expect of a car costing almost $120,000.
These include the DVD-based satellite navigation and MMI control interface system, adaptive Xenon headlights with LED daytime running lights, keyless entry and start, three-zone climate control, voice control system, front and rear parking sensors, leather sports seats and Bluetooth phone preparation.
Apart from its unique wheels and low sitting stance, an S4 stands out due to aluminium look wing mirrors, a body kit, subtle integrated rear spoiler and those daytime running lights.
The interior is black, with matt brushed aluminium inlays, there is a sports leather-wrapped steering with and a sporty instrument cluster with grey dials and white needles.