Ever since I was a kid, the interplay between computers and mechanicals in modern cars has fascinated me. Still does.
As a teenager with a box full of Motor Trend Magazine, computer-controlled all-wheel drive and individual-wheel braking and active differentials were often top of mind.
Fast forward some years to this past December, and I’m putting some miles on the latest version of BMW’s latest roadster, though it’s not exactly roadster weather in Northern Ontario.
Specifically, it’s the new Z4, in its newly-launched M40i (aka hot-rod) variant. It’s got a straight-six turbo that makes 382 horsepower exclusively for the rear wheels.
That’s a lot of sauce in a rear-drive car that’s not exactly anyone’s first pick for use in heavy snow, unless they’ve tried it. Sure, you’d probably store a car like this for winter, but enjoying it in winter instead maximizes your return on investment.
I’d be using this car to see how that interplay between computers and mechanicals would pan out when faced with some use in wintertime.
The equipped Blizzak rubber and included M-Sport differential with active lock laid a great foundation for winter grip. That rear differential responds in milliseconds to electronic signals that control when and how much the rear wheels are mechanically bound to one another.
That’s performance-car stuff primarily used so drivers can fire the car even faster out of corners.
But in the snow, that same piece of racy tech is deployed to lock the rear wheels together when you take off on snow or ice. It’s not AWD, but the bite is often surprising and seamless especially for such a small car. There’s minimal digging, and the traction control also permits plenty of wheelspin to keep momentum going.
It's also more stable in motion than some will expect.
Thank the 50/50 weight distribution. This engineering target enables better handling and more stability at high speed on a circuit. It also means that the Z4 is equally as heavy at both ends — not light in the tail. On snow and ice (and provided safe winter driving and the laws of physics are observed), this also means the the Z4 isn’t making any sudden moves, and isn’t using much of your bandwidth to keep on course.
On the highway, the sporty steering feels heavy enough to help keep the car feeling locked-in and stable, but also communicative enough that you can feel, say, a tire encountering black ice through the wheel. And though quick and precise, the brakes and steering are never touchy or twitchy, making it easier for drivers to be gentle with the controls when needed.
These are attributes common to many great sports cars, but also, attributes that encourage drivers to be present, involved, and aware of the goings on between the car and the road. When I learned how to drive, that was what winter driving safety was all about.
I’ll finish with two notes for the winter sportscar fans and aspiring Z4 owners.
First, use sport mode and sport traction control settings for winter powerslide duty and, second, bring a toque: other than the top of your head, the heater will keep you toasty with the top down, to about minus 10.
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