Car companies make some bold claims about their wares. Jeeps are “Trail Rated,” Acuras are tested in the near-Arctic conditions of Minnesota, and Mitsubishis are equipped to conquer Bolivia’s Death Road. Each deploys its own technologies, from all wheel drive to traction control, to accomplish these feats. Does any of that actually work?
Let’s start with the drivetrain. The terms “four wheel drive” and “all wheel drive” seem to mean the same thing, but there is a difference. Both systems power all four wheels, but “four wheel drive” usually refers to a system that is manually engaged; a lever shifts the car in and out of four wheel drive. This setup is preferred by off-road enthusiasts because, like a manual transmission, it gives the driver more control.
On the road, “four wheel drive” has some issues. Low gearing means low speeds, and systems designed for off-road driving have locking differentials. The differential allows the inner wheel to spin faster in a turn; when the differential is locked, both wheels turn at the same speed which makes turning more difficult.
Find out what's happening in Southeast-Brewsterwith free, real-time updates from Patch.
That is why most new cars sport “all wheel drive.” This system is permanent (no shifting) and controlled by a computer. The most basic versions shift power from front to back, but others can send power side to side, depending on which wheel has the most traction.
Even two wheel drive cars have their own supposedly weather-defying tricks. Traction control manages wheel spin at starting speeds to get a car moving. Stability control (usually called ESP) can brake individual wheels or cut power if the onboard computer predicts a rollover. However, there is only so much computers can do against the laws of physics; big SUVs are not sports cars.
Find out what's happening in Southeast-Brewsterwith free, real-time updates from Patch.
All of this technology helps, but it won’t make driving in difficult conditions foolproof. As a recent Popular Mechanics test demonstrated, all wheel drive and traction/stability control only help get a car moving; they don’t help it stop or handle better on snow. The difference in performance between all-season and snow tires was greater than the difference between all wheel drive and front wheel drive in otherwise identically equipped cars.
Electronic aids have not eliminated snow tires, or the need to be conscious of treacherous conditions. Ultimately, it’s up to the driver to keep the car on the road.
