Monday, 23 July 2007

Audi quattro: 27 years and counting...

By Dr Long

As the pioneer of four-wheel-drive technology, Audi set the transmission benchmark as early as 1980 with the launch of the Quattro coupe at the Geneva International Motor Show. Its enduring success on rally courses and racing circuits around the world proves that an innovation like the quattro is truly a practical technological application.

Prior to this, only a few exotic cars with a very small production volume and heavy off-road vehicles had permanent 4-wheel drive. By 1982, the Audi 80 quattro was the first volume production car to have permanent all-wheel drive (AWD). Audi celebrated the one millionth quattro car leaving its production line in 2001. And as they say, the rest is history. This figure is doubled by 2004 with quattro models having permanent all-wheel drive in conjunction with ESP (Electronic Stability Program), adaptive air suspension, Torsen centre differential, Haldex coupling, electro-hydraulic multi-plate clutch and aluminium chassis, among other things. Audi celebrated its 25 years of quattro in 2005 with its famous ‘gecko’ motif plastered on its safety driving training cars.

On the permanent all-wheel drive quattro, power is distributed as needed to all four wheels. This system provides high levels of active safety, and dependable traction on virtually all surfaces as well as excellent road holding, even in cross-winds. It is superior to manual all-wheel-drive systems because of this “permanent safety advantage”. The Audi RS4 and S4 quattro drive, with asymmetric/dynamic distribution of torque, transfers up to 100 percent of available driving torque to the front or rear axle if required.

It’s easy to see why all-wheel drive has the ‘unfair’ advantage over conventional driveline at only the front or rear axle. Normally, two-wheel driven cars, either FWD or RWD, have accelerative forces handled by just two wheels. Apart from this forward driving force, these pair of wheels also has to tackle cornering and braking forces. As such, we can foresee that eventually all these forces can easily overwhelm the pair of tyres’ grip limit, especially at high speed around corners while accelerating away. All-wheel-drive system like Audi’s quattro system distributes the engine’s torque to all FOUR wheels, thereby apportioning the accelerative forces by 50% lesser on each tyre. As a result, each wheel gets a higher reserve for handling ‘extra’ cornering forces before losing grip and breaking away, grappling for traction.

So how well does Audi quattro work in a country like Malaysia where we NEVER experience snow or blizzard? Well, the writer had a ‘revision’ with an A4 2.0 TFSI quattro recently.

Audi TFSI-powered A4s have always been great on the straights, highways and even mildly curved trunk roads. The power of turbocharging plus direct injection is always welcomed - with a smirk or grin - for those quick sprints and fast (and safer) overtaking manoeuvres. However, the substantial 280Nm worth of torque powering just the front wheels can be caught a little too busy especially when you hit tighter corners.

So, the A4 quattro’s driveline must be the cure that will address such ailments, yes? To a certain extent, I do admit that all-wheel drive provided a nicer balance to the A4’s chassis – and possibly weight distribution as well. However, the engine’s power is much sapped off, especially when driven in regular “D” mode. More often than not, you get that bogged-down feeling, attributed to the AWD hardware’s extra weight and permanent-four wheels propulsion.

On the highways, I would have preferred the alive-n-kicking feeling of its front-wheel driven brethren. But that’s only half the story since the quattro-specced A4 is undeniably the one to have when the sky starts to pour. Having driven on the N-S highway one dark and wet evening, I found the quattro confidently tracking on the third lane, overtaking cars as if the tarmac was dry. No wicked or rage-fuelled driving here, I was just unknowingly piling on momentum as if nothing mattered! Honest.

On winding roads, the permanent-four driveline felt busier as you exit corners. This makes the quattro quite a handful to handle. (Two Mercedes-Benz ASE 2007 trainers mentioned something about AWD vehicle having a little less ‘safety reserve’ in extreme handling situations even though they did admit it has better handling and of course, higher levels of grip. I wonder what the ‘safety reserve’ was all about.) The handling difficulty is compounded by the fact that the A4 has an unpleasantly - and undesirably - light and almost lifeless steering. Traction was aplenty – as is torque in 'S' drive mode - around the regular hilly bends that I tackle almost every weekend. Admittedly, I do appreciate the extra road holding forte but the A4’s suspension was acting like it had a mind of its own. With repeatedly tight left-right-left-right handers thrown in succession, the dampers were loosening up a bit too much to rein in the associated suspension rebounds incisively. As a result, there were even a little twitch and pitch to things. The much wanted taut and composed body control were sadly, missing.

Notwithstanding the fact that I may not have the required advanced driving skills to take the quattro to the maximum around those hilly B-roads, I still find myself more aligned towards RWD dynamics. While I admit the A4 quattro did handled better than the regular FWD A4 TFSI multitronic, I reckoned most of us with regular/standard driving skills would do better in the other two junior executives from the alternative Teutonic brands. Well, maybe the upcoming 2008 all-new Audi (B8) A4 has other technical trickery up its sleeves?

Related post:

No comments: