Open Road

AWD vs. FWD: Some drivetrains are more equal than others [video]

Open Road

I grew up in a really cold place. We had snow and ice and temperatures that got to 40 degrees below zero. And I grew up in the 1970s, which means that besides a few pickup trucks, all cars had one thing in common: rear wheel drive (RWD).

But my family was a bit oddball about cars, and in 1979 we got a Subaru wagon with all-wheel-drive (technically four-wheel-drive, as it had a transfer case), and then in 1981, we got an Audi Quattro.

And boy, did winter become a lot more fun.

I eventually became a professional rally car driver, and for more than a decade drove all manner of very fast all-wheel-drive (AWD) cars through all varieties of conditions: snow, ice, gravel, and tarmac. And I became a complete convert: every car in the world should be AWD. The balance and the traction are unmatched. There was no argument against it; relying on two-wheel-drive was like hiding your savings under your mattress – a reasonable approach until things start catching fire.

But then I moved to California. And I can honestly say in three years of living there I never once saw the need for AWD. In the dry, idyllic climates, you basically never become traction-challenged, and arguably the extra weight and complexity of an AWD system may cost you money in terms of fuel consumption and maintenance.

So…do you need AWD?

If you live anywhere that gets snow cover or ice on the roads, the simple answer is yes. While the single most important thing for you to have is a good set of winter tires, the next most important thing is AWD. I know a lot of curmudgeonly people will say “learn to drive!”--but I’m telling you that in slippery conditions, AWD is always worth having. Anyone who argues differently just hasn’t felt the advantages yet.

Most modern two-wheel-drive cars, for reasons of packaging and efficiency, are front-wheel-drive (FWD). These cars have an inherent handling trait of understeer, which is a good thing on public roads. Basically, if you try to turn too hard, or hit the gas too quickly and spin the wheels, or hit the brakes too hard and lock them up, the car will tend to do less of what you’re trying to get it to do. This is somewhat alarming, of course, but the good news is that if you just keep trying to do what you’re doing, as the car slows down (or, in the case of accelerating, speeds up), it will “come back to you” or begin responding more to your inputs. In layman’s terms, it’s idiot-proof.

A number of performance and luxury cars are still RWD--think BMW, Mercedes, and so on. In truly spirited driving, RWD generally has the best balance, although you should note that BMW and Mercedes-Benz also offer AWD versions of many of their models, and also that supercar producers like Lamborghini and Bugatti are strongly on the AWD bandwagon too, for optimal traction.

RWD isn’t as idiot-proof as FWD. This is where we traditionally learned to “steer into the skid”. Under braking you can get understeer, and under throttle, you can get tail-whipping oversteer; and on a few cars like older Porsche 911s, you can get one, then the other, and then even more of the other. Very exciting. Unless you’re near anything you could hit – then it becomes extremely exciting.

But there’s still a lingering question: if you live in a dry, temperate climate, does AWD handle better than FWD?

To answer that, we took otherwise identical Cadillac XTSs – one FWD, one AWD – to Willow Springs, one of the driest, hottest tracks in the country. I hammered on them around the track, and tried to get them to behave badly. Then we sprayed some water on the skidpad, and tried to break the cars loose there.

The verdict? Both cars exhibit neutral understeer. The AWD car actually exhibits slightly more of it. But the AWD car absolutely, positively would not misbehave in the slightest and allow the rear end to step around. Not in the dry, not in the wet, not with me using every ham-fisted technique in the book to try to make it slide.

Now, it should be noted that if we were hammering on, say, and AWD Mitsubishi Lancer Evolution, or an AWD Lamborghini Gallardo, or even an AWD BMW 5-series, we could have gotten the rear of the car to step out. But ultimately, the feeling would have been the same: more planted, more secure, more balanced for being AWD than any two-wheel-drive alternative. And we would have gotten that same result with the Cadillacs on snow or ice – I could have made both oversteer, but the AWD car would have collected itself up much more quickly and steered where I was pointing it.

Conclusion? Even though the AWD car is more stable, the FWD car is plenty predictable in the dry. You’re OK with two-wheel-drive in California. And probably Florida. And I would think most of Texas. But in places where you even sometimes get snow, I’d go with the AWD every time.

With apologies to George Orwell: “two legs good, four legs better.”

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