In snow, all-wheel drive beats two-wheel drive

Dear Car Talk:

I have a question for someone old enough to remember when rear-wheel drive was the only option and fishtailing was the norm in winter snows. Does front-wheel drive (versus rear-wheel drive) make a difference in handling for electric cars that have no engine up front (or in the back)? I'm on the waiting list for the Tesla Model 3 with rear-wheel drive, and I believe the batteries are distributed under the car, not in the front or back. There is an all-wheel-drive option, with no price tag listed. I do not drive up and down mountains in the snow, and most of the streets get plowed within a reasonable time frame; however, I do work in a profession that has no snow days, and attendance is required. Thanks. – Dolores

RAY: I wouldn't worry about getting to work in the snow, Dolores. At the pace Tesla is building these Model 3s, you'll probably be retired by the time yours comes off the assembly line.

All-wheel drive is always better than two-wheel drive in the snow. That’s because you double your chances of finding at least one wheel with traction.

But some front-wheel-drive cars, and even a few rear-wheel-drive cars, are plenty good enough for getting through mild or plowed snow. Will the Tesla Model 3 be one of those? Unfortunately, we won’t really know until some other Snow Belt guinea pigs try out their Model 3s.

Battery-powered cars, so far, have been heavier than gasoline-powered cars, due to the weight of the batteries themselves. And weight usually is an advantage in snow – in that it helps the car sink down through the snow and gain traction. With an estimated weight of about 3,500 pounds, that should be a plus for the Model 3 in snow. But the weight will be distributed along the length of the car, rather than right over the driven wheels, like on front-wheel-drive gasoline-powered cars.

On the plus side, like pretty much all cars these days, the Model 3 will have electronic traction control, which helps eliminate wheel spin in the snow. But preventing wheel spin electronically doesn’t help you if neither of your driven wheels has traction.

Of course, with two-wheel or all-wheel drive, you can improve your snow traction with four good snow tires – so plan on that either way.

Hopefully, your place on the wait list won’t come up until a bunch of other Model 3 owners have spent some time driving (or getting stranded) in snow. Once there are enough of them out there, you can Google “Tesla Model 3 in snow” and read about people’s actual experiences.

But if you have to make a decision without any additional information, I guess I’d lean toward all-wheel drive for you, just because you absolutely have to get to work when it snows. It’s going to cost you a few thousand dollars extra, but you already knew you weren’t actually going to drive off the lot in a Model 3 for $35,000, right?

And here’s what I’ll do. If you end up buying the rear-wheel-drive Model 3 and you’re not satisfied with it, I’ll buy it off you for half of what you paid. I know … you can stop thanking me now, Dolores.

‘Limp home mode’ limits car to very low rpm

Dear Car Talk:

I have a 2008 Saturn Outlook with around 88,000 miles on it. Right after starting it in the driveway, it began making a weird noise, and a warning came on the dashboard that said "Reduced Engine Power." When pushing the accelerator, the rpm wouldn't increase. I let the car sit for a little bit, started it again, and it ran fine. This is the second time it's happened. What's going on? – Mary

RAY: Thanks, Mary. You've actually answered a question that's troubled philosophers for years: If your '08 Saturn had reduced engine power, how would you know? Now we know that the answer is "the dashboard light comes on."

Your car went into something called “Limp Home Mode.” It’s the same mode you go into when you bang your knee on the neighbor’s piano bench during a dinner party.

Actually, Limp Home Mode is there to protect the catalytic converter – especially when it’s under warranty. If something goes wrong that has the potential to damage the converter, especially at high engine speed (like a condition where too much unburned gasoline is getting into the exhaust stream and could overheat the converter), the computer will engage Limp Home Mode, which limits the car to very low rpm but allows you to what? Limp home – if you’re not far from home.

Why did it happen? It can happen for a number of reasons. But the fact that it temporarily fixed itself with a restart suggests to me that one of your sensors is out of whack. So you can expect this problem to recur. It may start happening more frequently. And, at some point, a restart won’t fix it.

So limp over to your mechanic and have him scan it. He’ll plug his scan tool into the car’s computer port and read the code that the computer will have stored from this last incident. That’ll tell him whether it’s a cam sensor, for instance, a crank sensor or something else. Good luck, Mary.

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