By Winston Lee

Audi's revered "S" dates back to 1985 when its S1 Coupe started winning countless World Rally Championships.
Naturally, the carmaker capitalised on that and the first "S" production car - an S2 coupe - appeared in 1990.

More than 80,000 "S" cars have since been built, each with quattro all- wheel-drive and edgier drive trains.

However, in a strange marketing move, the "S" cars are no longer the flagship high-performance models. The honour now belongs to the RS line of Audis.

In an even stranger marketing decision, Audi decided there would be only one RS model at any one time. Over the past two years, it was the highly revered 420bhp RS4. This year, the honour will go to the 5-litre V10 RS6, with a whopping 580bhp.

"S" cars are now marketed as sporty, well-equipped variants that are refined and luxurious. They are not be as extreme as the RS cars but will still be distinctive and worthy of Audi's sporting heritage.

Until the new RS4 appears, the S4 rules the roost in the A4 range. Obviously, the car bears a resemblance to its lesser siblings. Chromed vertical double struts highlight the typical face of all "S" models.

Other unique features include a lower front apron, painted aluminium wing mirrors, twin tailpipes, new 18- inch or 19-inch rims and a bodykit.

Recaro seats with two-tone leather, brushed aluminium or carbon inserts for the fascia and chromed paddle shifters remind you this is no ordinary A4.

All pretty discreet but still highly effective. The luxury and quality of fittings are a notch higher, too. What is really special about the latest S4 is its all-new supercharged 3.0-litre V6. With 333bhp on tap, it sprints to 100kmh in just 5.3 seconds.

Audi engineers chose a Rootes supercharger over a turbo, as they wanted instant throttle response. Also, the space between the two banks of the 90-degree V6 was ideal for a Rootes unit.

The new engine is significantly more refined than the outgoing 3.2 V6. It revs freely and makes all the right noises, never sounding harsh or strained even when extended to its 7,000rpm limit.

The S4 is available with either a six-speed manual or seven-speed S Tronic DSG-style gearbox, which all Singapore-bound cars will have. S Tronic is virtually as quick as a manual, drives like an auto and is slightly more economical.

The low-speed stumble of many DSG gearboxes was not apparent on the relatively deserted streets of Mallorca.

Let's hope it will not manifest itself in Singapore's stop-start traffic.

Suspension revisions include stiffer dampers, springs and bushes. But the piece de resistance is the new electronically controlled rear differential.

Under hard cornering, the differential sends more torque to the outer rear wheel. This minimises the tendency to understeer or plough straight out at a curve.

Torque to the rear wheels is continuously varied to suit different conditions. The basic set-up is a 60:40 torque split between front and rear wheels.

Over the challenging Spanish roads, the S4 showed an uncanny ability to gloss over uneven surfaces without jolting occupants. It had an "on rails" feeling over the fast-sweeping curves. Setting the S4 to "Dynamic" mode did not cause ride comfort to deteriorate much. It did, however, give the steering more heft.

Unfortunately, this extra weighting was at the expense of on-centre response. It also made the steering feel a bit rubbery.

You can also select an individualised combo. My preference for quick commuting would be to dial in "Dynamic" for the transmission and suspension while leaving the steering in normal.

S4 models are available as sedans or wagons (Avant). Both are sleek and purposeful, with more than a hint of aggression. The Avant is my choice - it looks more elegant, offers more stowage and is, I dare say, just that bit classier.

The S4's main rival is obviously the BMW 335i. For on-the-limit driving, the 335i has the edge with its sharper steering and handling balance.

For all other driving conditions, the S4 runs it very close. The Audi is better looking, has a better quality cabin, packs more technology and would be a better ownership proposition.

This article was first published in The Straits Times on Nov 1, 2008.

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