Driver's Seat: Winter 2014-15: What have we learned?

Now that the spring equinox is past, it's a good time to ponder what we've learned from driving during the winter of 2014-15 - a winter to remember.

Let's review the material and clip and save it for the future. Then, we can pull this column back out when the snow makes an unwelcome return . . . next year, thankyouverymuch.

People drive too fast in bad weather. In good weather, I am a motivated driver. But when the snow starts falling, I find the recommended 45 m.p.h. on most Pennsylvania limited-access highways still far too high.

The numbers bear it out. A total of 17,832 crashes involving ice or snow/slush-covered roadways were reported in the state during winter 2013-14; 3,133 were in the five-county Philadelphia region, according to PennDot data.

Of the crashes statewide, 783 involved aggressive driving of some sort, and 30 percent of those involved driving too fast for conditions.

All-wheel drive is a good thing. I've long been a fan of front-wheel drive. I thought it was good enough. But this year, I managed to get a schedule of all-wheel-drive vehicles during the perfect storm of events, and I learned how wonderful it could be.

Dan Edmunds, director of vehicle testing for Edmunds.com, agrees. "Some of the vehicles I've tested - it's amazing how well they'll accelerate on snow compared to a two-wheel-drive version, even with front drive," he said.

For the snowluge of 2014-15, I enjoyed an all-wheel-drive Honda Pilot, Mazda CX-9, Nissan Murano, and, most surprising, a BMW 2 Series XDrive vehicle. That low-slung sports coupe turned out to be an unlikely hero. I drove it in a surprise storm on an inch of icy snow, and, using Sport+ mode for extra traction control, it didn't slip once.

How could that be?

Don Remboski, vice president for innovation R&D at Dana Holding Corp. in Maumee, Ohio, has given it a great deal of thought in his role at the automotive engineered driveline supplier.

He explained that engineers consider each tire a "contact patch," where the rubber literally meets the road. All-wheel drive gets all four contact patches working together, in theory, but because each may be on a different surface (ice, dry pavement, snow) the tires may not distribute the power uniformly.

Old-time four-wheel-drive systems allow each side of a vehicle to work independently - a setup known as the limited-slip differential. All-wheel drive allows each wheel to operate independently, and seamlessly, without any input from the driver.

Sensors at each wheel are tiny cogs measuring the revolutions of each tire. They transmit the information to the car's computer, which redistributes power when it recognizes one wheel moving much faster than others - or reacting to other combinations of movement as needed. Most systems apply some brake pressure to slow the spinning wheel, although more complicated systems will use overdrive or clutches to produce the same effect, Remboski said.

Traction control functions in a similar manner.

So how did the sporty BMW do the trick?

"Probably what you're seeing in the BMW is it's got very accurate control of all the contact patches," Remboski said.

Another big improvement for winter traction has been in tires, he said. Today's winter tires - which really could be called "snow-and-ice" tires rather than just snow tires - have better formulated rubber compounds for those surfaces.

Laws of physics still apply. Haters, don't queue up the e-mails scolding me for encouraging bad winter-driving behavior. I hope to ferociously combat that other winter animal, the Overconfident SUV Driver.

Everyone has seen that driver morph into SUV Driver in the Ditch. Remboski and Edmunds mentioned the stereotype without prompting. All-wheel drive and traction control are excellent assistive devices designed for getting the vehicle moving. No matter how wonderfully they work, though, vehicles still stop in about the same distance on snow and ice, Remboski said.

"It's easy for someone to fall into a false sense of security - it pays to be extra cautious with attempting to stop," he said.

Edmunds agreed. His daughter is learning to drive, and he has reservations about an all-wheel-drive vehicle for her.

"Part of me thinks I'd almost rather have her in a two-wheel-drive car when she's learning," he said, "just to have her aware of how little traction there is in certain conditions."