Traction control is a favorite selling point for most luxury and some common or garden variety cars on the market today. Our review will cover some of the most popular, as well as giving driving tips for the four-wheel drive novice.
While in the late years of the XXth century differential locking to control traction was a prerogative of off-road or utility vehicles, mostly manually-operated as in the Land Rover and Range Rover models, the introduction of electronic traction control means that even a sedate sedan can feature traction control or four-wheel drive without worrying too much about the cost.
The point about four-wheel drive is to regulate the rotation of all wheels so as to allow them to work at different speeds. Taking a bend, this speed difference will make the car very easy to handle and much more secure in wet or icy conditions. This is obtained by use of a differential, which permits one input shaft (the engine’s drivetrain) to drive two output shafts independently. Traction control came into play as a refinement of this principle, and solved the problem of slippage of one or more wheels (on icy roads for example), which four-wheel drive could not by itself prevent.
Traction control means each wheel can be independently braked, hence slowed down, when it slips and as a result turns faster than the other wheels. This is achieved by locking the differential, and advanced electronics are now able to do this automatically, thanks to sensors that pick up the rotation differences and lock the shafts. In the multi-plate clutch design, the shaft lock generates a small jolt when it activates, which can disturb the driver. Viscous coupling units, another widely-used system, are smoother but tend to degrade quicker than a multi-plate clutch. A third system, the Torsen system, is used on many luxury cars, as Audis for example, where it is joined with advanced electronics to deliver top-level performance.
If you are thinking sports cars, you will be spoilt for choice of four-wheel drives. The Ferrari FF, the first Ferrari to feature four-wheel drive, in 2011, is the most recent supercar to offer automatic traction control. Lamborghini started out a long time before, with the Diablo in 1991, the same year as the Bugatti EB 110, and continues today with the Gallardo. Porsche beat them all in 1987 with the 959 (the same year of the introduction of the first Mercedes 4-matic model), and currently offers both the coupe 911 and the sports sedan Panamera with four-wheel drive. And of course Porsche was the first of the supercar manufacturers to launch an SUV, the very successful Cayenne (2002).
Among other luxury brands, Audi has had probably the most successful sporting career, as well as one of the longest. The first Audi Quattro coupe began its rallying victories in 1980, and Quattro has been the trademark for a long series of successful sports, sedan and estate models. The Audi A6 Avant (estate) Quattro is a paradigm in its class. It sports a top speed of over 240 km/h with a smooth automatic 6-gears transmission system and a turbo-charged V6 diesel engine that handles like a kitten but roars like a tiger when you want it. The traction control works wonders. Used in snowy conditions (up to 10mm of fresh snow) it will keep all four wheels rotating in unison so that even if your tail-end slips a bit (not easy, you must have been overeager with the gas pedal!) control is instantly regained and torque distribution remains ideal.
With electronic control, since you don’t engage the differential lock manually, you don’t have to keep your senses tuned to the traction conditions so much but need simply to use the accelerator judiciously to avoid over-steering.
Other less prestigious brands offer electronic traction control on many models. For example Japanese make Subaru, which made a name for itself in rally racing, features the Impreza, an otherwise unassuming sedan, and the estate model Outback with four-wheel drive and excellent electronic traction control.
Even FIAT, a traditional maker of sedate, rather than sporty cars, features four-wheel drive models even at the lower end of the range, with the diminutive Panda (since the 1990s), as well as the recent Freemont, born from the joint venture with American giant Chrysler.
So if you want to drive in traction-controlled comfort, you can do so starting with a FIAT and reaching for the stars with a Ferrari.
