What's the Best Car for Slippery Conditions?


I am from Québec in Canada. Winter conditions can be heavy sometime here, with snow, ice & slush. I am not a fan of SUVs or pick-ups. I am looking for a good 4x4 car. What do you suggest? - Jonathan


Easy answer, Jonathan: Subaru. Seriously, this is a no-brainer. The Impreza, the WRX or the Liberty.

Left to right, above: Subaru Impreza, WRX, WRX STI and Liberty

We don't get much ice and snow in Australia, but we do get other common low traction conditions - like gravel (which approximates driving on ball bearings, at times) and also rain, which makes all surfaces slippery, but especially unsealed surfaces.

Basically, in the range of Subaru cars listed above, the Impreza is a nice little car (Corolla- and Mazda3-sized) that's also affordable, while the Liberty is a much more luxurious proposition (more a Mazda6 competitor). The WRX is an awesome performance car that is just sensational value, and the WRX STI is an even more awesome performance car that's still unbelievable on the value front.

Subaru’s big advantage in low traction situations is the company's symmetrical all-wheel drive system, which drives all four wheels all the time. Effectively, for any given amount of driveline effort (torque) coming out of the gearbox, having all four wheels doing the driving halves the tractive effort at the wheels, compared with a 2WD car. (This is a generalisation - other factors are at play at times, such as weight transfer on heavy acceleration, and also torque reactions in the driveshafts.)  

In simple terms, you’re half as likely to spin the wheels or lose traction under load with symmetrical AWD. It's ideal on snow, slush and ice (and also gravel and mud ... or just a normal suburban road that's wet: rain lubricates everything).

Most other AWD vehicles (generally SUVs) from other brands have what's called 'on-demand' AWD. (These include some really good SUVs, which I routinely recommend,  like the Mazda CX-5 >>, Hyundai Santa Fe >> & Tucson >> as well as the Kia Sorento >>) This means the vehicle is essentially 2WD (usually front drive) until those wheels start to spin. When that happens, the AWD system kicks in, generally using a reasonably fast-acting clutch to transmit drive to the other end of the vehicle.

Unfortunately, on-demand systems are not nearly as effective in slippery conditions because they have to wait for wheelspin to occur before they engage. In some conditions (typically mud and sand) the wheelspin occurring before the AWD system engages can be enough to bog the vehicle. (This is not generally a problem on ice/snow when there's a hard road just a few inches underneath.)

Some on-demand AWD systems have a centre diff lock, which allows the driver to press a button on the dash, thereby engaging the lock. When locked, the front and rear propshafts turn at the same speed (they're locked at exactly the same speed). That's a real advantage in those sandy, muddy conditions outlined above - but you can't drive around like that all the time. If you do, you'll damage the transmission, because on a high-traction surface the front end and the rear end need to turn at different rates when cornering. On a grippy sealed surface, locking the centre differential (by pressing the 'AWD lock' button) prevents them from doing that, which can easily break something.