Is All-Wheel Drive Safest?
AWD can help get you going, but stopping is a different story
We’ve all seen the ads: a car or SUV blasting up a snow-covered mountain road, exploding through snow drifts as if they were cotton candy. A husky voice-over proclaims the unstoppable, take-it-anywhere advantages of the vehicle’s all-wheel drive (AWD) system, while a smiling family emerges from the car, ready for a day of extreme snowboarding.
But once you peel away the marketing hype, the real-world safety benefits of AWD may simply depend on where you live.
The advent of AWD
In the ‘60s and ‘70s, there was a definite answer to the question of which drive system was safer. With the weight of the engine and transmission located directly over the wheels powering the car, a front-wheel drive car could maintain good traction in all types of weather. When roads got sloppy, front-wheel drive vehicles also were less prone to fish-tailing due to oversteer — the tendency for a vehicle’s rear-end to kick out under acceleration or while turning. It also didn’t hurt that most front-wheel drive cars were smaller and nimbler and got better gas mileage than the rear-wheel-drive land yachts that ruled the roads of the era.
But in the ‘80s and ‘90s, several car manufacturers began using AWD systems that directed power to all four wheels and distributed that force based on which wheels actually had traction. This simple, common-sense idea meant a huge jump in both performance and safety. Drivers discovered they had more control in rain and snow and significantly more traction on ice.
So that means all-wheel drive is safer, right?
It’s all relative. Safer than your uncle’s ancient Oldsmobile sedan? Absolutely. However, some of the technology that gave AWD such a stark advantage two decades ago is increasingly common on many front- and rear-wheel drive cars. High-tech differentials — the gears that distribute power between wheels — combined with electronic sensors monitor wheel slip in real time, enabling the car’s computers to detect a skid and adjust power to correct it before a driver even has a chance to say “Oh no.” (Most newer crossovers and SUVs use additional sensors that watch for potential rollovers, the type of accident that traditionally made these taller vehicles less safe than large sedans.)
That said, multiple independent tests and years of rally competition have shown that AWD vehicles still have better traction in snow and ice.
The downside of AWD
Many drivers don’t realize that AWD vehicles won’t stop any faster than two-wheel drive vehicles — and heavy SUVs need even more distance to brake safely. The additional traction will help you accelerate faster but won’t help slow you down. This misconception may be one of the reasons that all-wheel and two-wheel drive versions of the same vehicles tend to have similar rates of fatal crashes.
Three smart ways to maximize your road grip
Match the horse to the course. If you regularly need to drive in deep snow or slog through sand, mud or along rough roads, four-wheel drive, increasingly found only on the largest pick trucks and SUVs, may be your best bet — even better than AWD. (What’s the difference? In short, most AWD cars are front-biased, with the front wheels getting a greater percentage of power during normal driving. If wheel sensors detect slip, the car will send power to the wheels with traction. In a four-wheel drive system, power is sent to only two wheels during normal driving — usually the rear — until the driver determines more traction is needed. With a button, the driver activates a center-mounted transfer case that sends power to the front axle.)
For nearly everyone else who encounters sloppy stuff occasionally, an AWD vehicle should perform well. A two-wheel drive vehicle with decent winter tires can handle most light snow and patches of ice. But the versatility of AWD has started to gain fans among large fleet buyers. After years of relying on large rear- or front-wheel drive vehicles, many police departments are choosing AWD versions for patrol cars, especially since most newer AWD systems have sharper handling than in the past.
Choose a car with electronic stability control (ESC). This combination of antilock braking systems, traction control and torque distribution increases safety when cornering and on wet or icy surfaces, regardless of the drive type. Research by the Insurance Institute for Highway Safety found “ESC lowers the risk of a fatal single-vehicle crash by about half and the risk of a fatal rollover by as much as 80 percent.” Various types of ESC are standard on 2012 and later passenger vehicles (including light trucks) sold in the US.
Wear proper at-tire. The right tires are crucial for safe operation, no matter the season. Check wear and inflation regularly, and remember that a car’s ability to both start and stop safely is dependent on the four patches of rubber that touch the road. Good winter tires on a front- or rear-wheel drive car will provide better traction than all-season tires on an AWD car.