Heir Triggers - Audi S4 vs BMW 335i

Remember cornering an Audi executive at dinner a few years ago and grilling him about the disappointing dynamics of the (now previous-generation) S4.

Surprisingly, rather than stoutly defending Ingolstadt's honour, he freely (although off the record) admitted it was dynamically hamstrung and that a BMW 3 Series was a much sharper drive. Primed with a little liquid courage, I pushed a bit further.

The flared wheelarches and tough-guy swagger, I argued, promised a proper sports sedan experience, but fell frustratingly flat in delivery. That bellowing 4.2-litre V8 and rear-biased all-wheel-drive system gelled on smooth roads, but a punishing ride, wooden steering, and a total inability to deal with bumps and corners simultaneously killed the love.

The sharp-suited exec sighed and nodded, but even back in 2006, he clearly knew something was brewing back in Ingolstadt. He leaned over and whispered that BMW was going to face some much stiffer competition from Audi in the years to come. Draining the last of his shiraz, a wicked little smile played across his lips and he told me the next S4 would flip the status quo. Not that this kind of car-company spin was surprising, and I've heard plenty of bare-arsed lies at industry dinners, but even back then I got the impression there was some substance behind his bravado.

Fast-forward three years and it takes just one strafe down a twirling ribbon of mountain pass behind the wheel of the new S4 to prove his words prophetic.

But clearly Audi's tilt at sports-sedan supremacy hinges on defeating another German giant, and the S4's sparring partner is sucking up 98 RON as I pull into the servo in the early hours of a crisp July morning. Sexy, gunmetal grey paint glinting in the sun and aggressive bodykit hunkered over the tarmac, it's all tautly drawn surfaces and sporting intent. Man, this thing looks good. The badge on its rump reads 335i.

BMW has been the undisputed heavyweight champion of sports sedans for close to 50 years. Since the first four-door 1500 in 1962, through to the legendary 2002 turbo of '73 and across successive generations of M3s and M5s, BMW has spiked pulses and stirred trousers the world over. But even the lesser models have always been cast from the same mould, woven from the same strand of tightly-focused DNA. Any enthusiast will tell you fun lives largest in rear-drivers and BMW has a blue-ribbon pedigree in delivering finely honed rear-drive sedans.

Audi has stuck with its traditional rear-biased all-wheel-drive performance mantra, but has given the S4 a ground-up rebuild. Based on the company's new mid-sized platform (also underpinning the A4 and A5 ranges), the naturally-aspirated V8 has been turfed in favour of a supercharged, direct-injection 3.0-litre V6 (which, confusingly, is badged as a 'V6T'). Power drops slightly from 253kW to 245, but torque ramps up 30Nm to 440. More telling, however, is where that blown grunt is produced. Max torque is on tap from 2900-5300rpm, then at 5500rpm peak power steps in and stays on hot and strong until redline at 7000rpm.

Now, swapping from a V8 to a blown V6 isn't going to refreeze one single square centimetre of polar icecap, but it does make for a more wallet-friendly 9.4L/100km ADR sticker (down 24 percent). But keep the new V6 spinning in the meat of its power zone and that figure will skyrocket. The Audi recorded 14.1L/100km over our test loop, while 335i's twin-turbo six slurped 11.3L/100km. Chalk one up for BMW.

Why did Audi choose the less sophisticated supercharging route when almost every other manufacturer is playing with turbo tech, and Audi itself fits plenty of its other models with hairdryers? Packaging and weight are two key reasons; with the Roots-type blower nestling neatly between the banks of the 90-degree V6 and the entire engine weighing in at just 189kg. Throttle response also benefits - the V6 whip-cracks like it's wired to your right ankle with a crispness the BMW's turbo six simply can't match.

The 3 Series range was revised and reloaded late last year with a host of subtle cosmetic changes that crank up the dial on the sedan's kerbside swagger. I'd love to list for you exactly what BMW has changed, but the press kit was written in some bastardised, incomprehensible form of English that probably got someone in marketing a promotion, but left me scratching my head. I'm still not sure what 'new width orientation' means, but I did decipher that a wider rear track, new side sills, new headlamps and tail-lights are among the more significant changes.

What hasn't changed is the 335i's superb drivetrain. The 225kW/400Nm twin-turbo 3.0-litre straight six is left untouched and still hooks up to the slick-shifting six-speed ZF auto (the 335i coupe and convertible are available with Bee Em's seven-speed dual-clutch 'box), making this one of the sweetest drivetrain combinations available. The two equi-sized, low-inertia turbos - each force feeding three cylinders - spool up from 1300rpm, meaning turbo lag is virtually nonexistent and that creamy 400Nm wallop of torque stays under your right foot until 5000rpm. This engine is more flexible than a Chinese gymnast, and while it may cede 20kW and 40Nm to the S4, the BMW is 135kg lighter than the bigger-bodied S4. As a consequence, it feels beefier in the mid-range, chewing tarmac as the turbos whistle distantly, then giving way to a metallic snarl as the tacho charges to redline and the engine wails like a BMW should.

But as sweet as the 335i's engine is, it can't touch the S4's ballistic top-end pace. Below 3000rpm, the Audi's 3.0 TFSI doesn't feel any more special than the 3.2-litre V6 fitted to top-end A4s, but as the crank spins into the upper reaches, speed seems to multiply exponentially and the final charge from 5000-7000rpm is like being strapped to a Tomahawk missile. The Vbox-verified figures are 0-100km/h in 5.05sec, with the 400m marker gobbled up in 13.19sec. The BMW doesn't exactly hang around at 5.52 and 13.68 seconds, but the list of cars left sucking fumes by the S4 stretches from any HSV on sale to the Maserati Gran Turismo. And it's breathing hot on the neck of any Porsche 911 not spinning turbos...

Some of the credit for this scorching straight-line speed must go to the new seven-speed dual-clutch 'box. Despite being a little recalcitrant and clunky around town (particularly moving away from standstill), in max-attack mode shifts are eye-blink quick and virtually imperceptible; only the rise and fall of the V6's buzz-saw snarl and the relentless sweep of the speedo needle indicates cogs being swapped. The Bee Em's torque-converter auto creams the Audi's for smoothness around town, sliding seamlessly between ratios, but is outgunned by the S4's rifle-bolt changes, and the twin-snail straight six can't match the blown V6's high-rpm heroics.

But the Audi's real party trick, the reason BMW should be worried, is the way it now goes around corners. The S4's transformation is nothing short of a revelation, and the key to its dynamic revolution lies in the revised all-wheel-drive system (which can send up to 85 percent of torque to the rear wheels, or 65 percent to the front axle) and the optional new active rear 'sport differential' which juggles torque between the rear wheels. The propeller heads among you will want to know that this trick diff uses a variety of sensors monitoring steering angle, lateral acceleration, yaw angle and road speed to calculate which wheel needs a torque injection, and is capable of sending nearly 100 percent of drive to either wheel. But all you really need to know is that it works. And then some.

Pinned hard in a corner, you can feel the diff shuffling drive to the outside wheel as the tyres squirm into the tarmac, allowing the S4 to fire out of bends with an almost Evo-like ferocity. There's a fluency and agility to this German that marks it as a true driver's car, and the added steering effect of sending drive to the outside rear wheel means the S4 carves corners like Dad attacking the Christmas turkey, just minus all the sweating and swearing.

Long sweepers tackled close to the limit will initiate the push into understeer, but tighter bends are a playground and the playful, adjustable chassis is a peach. Lift off the throttle and the nose tightens its line as the bum smudges wide, then nail the throttle to execute delicate apex-clipping drifts. Or, choose to drive straight and the power-down exits are electric and overall grip levels huge.

Tearing back up the pass, criss-crossing tight 30km/h hairpins and stretching out onto fast, white-knuckle sweepers, the BMW's twin-turbo six is sucking hard on the cool winter air and offering a very different experience to the S4. The first thing you notice is the contrast in steering between the two. The BMW's steering is heavy and meaty around town, but lightens too much at speed and under load, which strikes me as the opposite of how it should be. There's always a fine grain of feel through the thick-rimmed wheel, and turn-in is sharper than that of the S4, but the hair-trigger steering tugs and tramlines and you feel like you're chasing the nose through corners, sometimes making it difficult to find a smooth, steady line.

The rear-drive chassis is sweetly balanced, though, and throttle control is linear and consistent, despite the twin huffers forcing 400Nm through rear rubber only. There's a certain delicacy to the 335i's dynamic behaviour that the S4 lacks, but in terms of outright grip and pace, the Audi is simply on another level. The BMW is still a fine sports sedan, but on the optional M Sport suspension and 18in wheels, the ride is borderline harsh over scarred urban arterials and feels nervous charging over back roads. The rear rebound is too fast, bobbing sharply over dips and humps and feeling disconnected from the sniffer-dog front end.

The S4 was fitted with Audi's optional ($6700) 'Drive Select' system, which bundles adaptive three-mode dampers and active steering with the brilliant rear differential. This system allows comfort, auto and dynamic modes for the steering, gearbox, diff and dampers. The Audi offers a noticeably superior ride (now there's a sentence you don't see very often). The springs and adaptive dampers round off larger impacts with a deft touch - even on the stiffest setting - and keep body movements firmly in check without punishing kidneys. Around town, the ride is stiff-legged even in comfort mode, but it's an acceptable trade-off for the apex-clipping dynamics.

The S4's active steering isn't as successful. It's pleasingly light in comfort mode for tooling around town and parking, then firms up nicely in dynamic mode when the red mist clouds the eyes, but there's virtually no connection and the weighting is artificial, lacking the BMW tiller's trace of feel.

The Audi's dynamic superiority, however, does come at a price. Fitted with $12,578 worth of options (Drive Select, upgraded audio system, sports seats, carbon-look interior trim and metallic paint) the final figure jumps to $131,478.

Our 335i kicked off from a lower base ($107,300) and added the $4800 M Sport package (including sport suspension, 18in alloys, M steering wheel, and sports seats), along with metallic paint ($1840) and sunroof ($2920) for a $116,860 tag.

But as accomplished and undeniably bloody quick as the S4 is, there's still a certain Audi-ness which left me slightly cold. It's difficult to pinpoint, although the numb steering and excessively assisted brakes certainly contribute, but it's the over-arching sense of clinical efficiency that makes it difficult to truly bond with the Audi. It lacks a kind of mechanicity if you will; its true character buried under a layer of refinement and Germanic efficiency. The chassis may be a peach, but that ultimate, eye-popping tactility is missing. For some, this may be a positive attribute, but I craved the extra touch of involvement.

Nevertheless, Audi's victory here is emphatic; the S4 is a stunningly rapid and cohesive sports sedan. The 335i still deserves praise, but the game has moved on and Ingolstadt has rocked the status quo.