Hacker News Reader

I'd expect overpowering the front wheels is much less dangerous than the rear, regardless of engine type. Front wheel is pretty much the norm now in the vanilla car market, partly because they're safer.

Also, just for driving dynamics, front wheel is better for day-to-day stuff. More predictable, easier to correct, easier to control on rough or slippery surfaces, ... I'd rather drive a front-wheel car without traction control than a rear wheel drive one.

Maybe I'm missing something here, but a small family car like this should be front-wheel drive. Also, front wheel can be pretty sweet in a small car with a peppy engine.

Front wheel drive is the norm for small cars because it is cheaper and more space efficient. Furthermore, the problems with front wheel drive a proportional to the ammount of torque the car produces. A lot of small economy cars are designed not to be very powerful, so front wheel drive is not much of a problem.

But small cars that are designed to be performance cars from the beginning tend to be real wheel drive cars. See for example, the mazda miata, the toyota mr-2, the prosche cayman/boxter, the alfa romea 4c, etc. If you look carefully at powerful small cars, you will notice that the ones designed from the ground up to be performance cars tend to be real wheel drive, the ones that are designed merely as an upgrade of a less powerful economy car are often front wheel drive.

The cost efficiency and space benefits of front wheel drive are mostly related to the particularities of internal combustion engines. For an electric, these are not that much of an issue.

And the steering problems of powerful front wheel drive cars are very real.

Torque-steer is a packaging problem; the difference in half-shaft lengths between the left and right hubs in most transaxle setups causes an uneven application of torque. If manufacturers choose to employ them, there are solutions to the problem:

- Many AWD vehicles, and many 2WD Audi and VW cars, use a traditional longitudinal setup with equal-length shafts driven from a transaxle mounted in the rear of the engine.

- Power-assisted steering can be employed to counteract torque-steer by receiving the current torque application as input.

Like you said, an electric vehicle has neither of these problems, because they do not have to package a transaxle to one side of an ICE-driven crankshaft. There is no reason to believe that the Bolt exhibits torque-steer, and nothing in the article corroborates this suspicion.

The other benefit of FWD vehicles is that understeer is much, much easier to recover from than oversteer. RWD vehicles tend to snap-oversteer the other direction when the untrained driver lifts off the accelerator too quickly; a common occurrence in YouTube videos of Mustang and Corvette conventions. Understeer can easily be recovered from by lifting off the accelerator in the same way, putting more weight on the front wheels and increasing available traction.

It is not only a packaging problem, there is a fundamental physics problem that cannot be avoided. When power is produced by the front wheels they create a force between them and the ground. This is the force that causes the car to accelerate forward. But this force also puts pressure on the stickiness on the forward wheels and makes them want to slide.

If you apply a lot of torque you start getting microslides, or momentary losses of traction which reduce the front wheels ability to steer the car and cause torque steer and understeer.

A lot of the problems of oversteer you see in youtube videos and the like are really just very extreme cases. I doubt the Bolt, even with its electric motor, will have as much torque as a the souped up mustangs and corvettes that you usually see at those conventions.

In general, for the same amount of torque, oversteer is much better than understeer, because it does not cause nearly as much loss of steering (and the little loss it causes usually goes in the right direction, i.e., helping you turn). Oversteer is the result of the rear wheels sliding, and the rear wheels are not as crucial for steering as the front wheels. Thus microslides in the rear wheels will not cause such a loss of steering authority.

I remember i test drove a 200 hp front wheel drive audi, and it had noticeable understeer and torque steer problems. Then i test drove a 300 hp rear wheel drive infiniti, and it had no oversteer problems even though it had much more horsepower and torque.

Of course you can always cause dangerous situations with oversteer, but you need much more power and torque to do it.

What you are saying, in simpler terms, is that the traction circle in FWD vehicles is limited by the fact that the same contact patch must handle both acceleration and steering. And that's true. This makes FWD setups prone to understeer. Everything you describe services this truth.

What's not true is that torque-steer is caused by lots of torque overcoming available traction. The same torque is applied to both wheels in the absence of unequal-length half-shafts. You might induce understeer with the application of torque, but it will not induce a force which changes the steering angle moreso than the same understeer situation would induce on a RWD vehicle, and that's a function of the suspension setup, and mostly dependent on caster angle.

Thus I submit that torque-steer is not an inherent flaw of FWD design, but of the most common packaging design in ICE vehicles. It's easy to conflate the two.

I wish it caused oversteer! The reason front-wheel drives are so pathetic to drive is because it causes understeer, but which is what also makes them safer than rear-wheel drives. I have an e-Golf with loads of torque at the front wheels, and I can spin the tires easily whether going straight, or in a turn (and coming off of speed bumps). I so wish the car were rear-wheel drive (edit: in the sense that I could have a rear-wheel drive; I don't actually want a mass-production e-Golf to be rear-wheel drive).

You are right. I meant to say understeer. I changed it. Thanks for pointing this out.

I have yet to drive a front-wheel-drive vehicle that cannot exceed available traction under wide-open throttle at low speeds. I used to own what was once the cheapest car in America (the fourth-generation Toyota Tercel); its measly 94hp could easily perform burnouts when dumping the clutch at high RPMs.

In fact, I would suspect something to be entirely wrong with a car lacking this capability. A vehicle with even less torque than that Tercel would have problems passing, driving up steep grades, and maneuvering slippy situations. No American consumer would purchase such a car (if this were the 1970s I would not be making the same statement).

If you can't peel out with a standard something is wrong or broken. Rev it up, dump the clutch, listen to physics working it's magic. The bolt and pretty much every economy car sold in the US comes with an auto. You usually need a wet road to peel out in a 90s tercel with an auto and if it had some sort of traction aid (limited slip, or even a detroit locker for sh*ts and giggles) you probably wouldn't be able to peel out with an auto at all (well, maybe with a neutral drop you could, but that doesn't count).

and BTW, a Prius meets all the criteria you described. They actually have a lot more "go" in the power-train than they give the driver access to since they're trying to put a lower bound on fuel economy. They have about the same passing power at low speed as an 80s pickup, but the 80s pickup will be a lot faster off the line (gearing and flat torque curve) and be worse at highway speed (bad aero) Nobody notices this stuff because very few people actually floor it.

FWIW they give most economy cars a really tall 1st gear to make it harder to peel out from a stop (e.g taking a right turn into traffic in the rain) and I expect the bolt to be no exception. Consequently they're very slow off the line.

It's harder to apply the immediate sort of torque needed to do burnouts in automatic transmissions (in this case, transaxles) because they have low-end-torque-sapping devices called torque converters. These are opposing arrays of fins bathed in automatic transmission fluid; when power comes in the input side, the input fins spin, forcing fluid into the output fins and causing them to spin, and finally delivering torque to the input end of the transmission (transaxle).

Direct-drive electric vehicles, just like standard-transmission ICE vehicles, have none of this nonsense, which leads to part of the "legendary torque" association (the other part being the flat torque curve).

So being alarmed at the ability of a vehicle without a clutch or stick-shift to activate traction control when flooring at low speeds is not a cause for concern, nor is it damning of the Bolt's design, nor is it damning of FWD electric vehicles as a class.

He said the traction control engaged when accelerating out of some corners. That may be the result of high torque or a badly designed car.

Probably high torque. I can cause tire slip by stomping on the pedal in my Fiat 500e. You just have that much torque and it's available instantly. The low rolling friction tires probably don't help. However, the good news, is that electric acceleration is instantaneously responsive, so you can have the driving pleasure of optimizing how much acceleration you can get away with.

It's not a sports car, it's a commuter vehicle. Understeer is safer, since it's less likely to get an inexperienced driver into trouble. Yeah, it's stupid if a little car like that engages traction control when accelerating, but if the wheel is at full lock, it might just be a product of the suspension design and the differential design, and it'll probably be fine for all the people that commute in it.

I think when you said oversteer you meant to say understeer. Excess power on wheels that are turning causes them to skip and understeer.

That said, I'd be completely shocked if the car wasn't FWD. Most auto makers+small car=auto FWD.

Large portions of people that live where it snows will only drive a front wheel drive (or all wheel drive) vehicle. My first car was a $400 rear wheel drive beast, so it doesn't bother me - but a lot of people think I'm crazy driving my (rear wheel) Camaro in the winter.

Yep, this. I don't care about crazy good performance, but do want something I feel handles reliably in snowy and icy conditions.

Call me an unskilled driver, but I don't feel as confident in bad conditions with rear wheel drive.

You're an unskilled driver.

Traction is traction. No matter how a car handles it'll handle the same way on every surface, the traction threshold will be different. No matter which wheels are driven turning and braking is the same. In a straight line it front/rear doesn't really matter. RWD will slip out, FWD will just spin and in either case the driver (the one's that aren't the worst of the worst) will lift off the throttle before anything bad happens. In a modern car traction control will just work it's magic and you wouldn't even know. Ditto for turning from a stop. The driven wheels are irreverent to turning while slowing. The problem is in a long sweeping turn that the driver wants to accelerate out of, like a highway ramp. FWD will just plow straight into whatever is outside the turn. RWD will do the same thing but the car will be oriented differently. No matter which wheels are driven if you break traction in a turn you're going to go wide, better hope you've got enough space to correct it. The safety advantage with understeer is that if you do something monumentally stupid (e.g. drunk guy takes highway off ramp at 90mph) the front of the car with all it's crash test safety will be between you and the consequences of your actions.

The RWD vs FWD thing is more of a "what I don't know can't hurt me." The novice won't notice a little bit of understeer whereas anyone will notice a little bit of oversteer and everyone who can't apply a reasonable amount of self control to their right foot should bend over, grab their ankles and spend their money on some snow tires.

The Miata club of Alaska was featured in one of the car magizines (I forget which) and they basically said "Everyone that thinks we're insane for driving these cars year round in Alaska should know that the design characteristics that help maximize use of available traction in the dry don't stop working in the snow."

You are overlooking weight distribution. The traction of a given tire on a given surface generally increases as the weight on that tire increases. Given two otherwise similar cars, one with the engine over the drive wheels, and one with the engine over non-drive wheels, the former will generally have an advantage in snow, especially on hills.

Agreed, but if we move the conversation back to electric cars - they might not have the same weight distribution, right? The Tesla uses direct drive on the wheels (the Leaf seems to use a more traditional "one motor in the front" configuration though), and then you have the huge battery spread out over the floor

Ever watch one of those YouTube videos of RWD cars on proper winter tires out-tractioning AWD cars on summer / all-season tires?

I survived the Atlanta snow storm a couple years ago turning a 35 mile commute into 50+ miles due to detours in a BMW on summer tires... The only confidence I felt was that I was going to end up stuck somewhere, but adjusting driving style to conditions goes a long way and then it's just the luck of not getting hit by someone who didn't.

> a lot of people think I'm crazy driving my (rear wheel) Camaro in the winter.

It's because you are, maybe, depending where you live.

I daily drove a RWD Alfa Spider for 5 years year-round in Boston, and a Mercedes diesel sedan (also RWD) for 4 years. The Alfa had a (mechanical) limited slip differential and the MB had snow tires, but that was it.

I could drive either of them until the snow got deep enough to high-center the car. It's not rocket science.

People don't realize how much difference good snow tires make. I'd rather have a FWD car with Nokian tires than an AWD car with all seasons.

Thing is, in the places mentioned, there aren't hills like we have where I live. Makes a huge difference in snow and icy conditions.

It also matters when winter temperatures tend to hover around the freezing point vs. well below. It's hard to gain traction when the surface is slippery rather than hard frozen but essentially dry.

I've owned RWD vehicles (e.g., Volvo) in the past, I mean, good cars but useless trying to go up/down a steep incline just after a wet, sloppy snowstorm. To those professing to "know how to drive in snow" with RWD, I've offered the challenge of driving up to my house when our streets are coated with ice-encrusted snow. Nobody has yet taken me up on it.

Even FWD can be insufficient. I've insisted on all-wheel drive at a minimum. My near-ancient 2003 Honda Pilot has a locked 4-wheel range in low gear. There have been times I needed it, and even a few cases where I also had to use chains.

Whether RWD will suffice ultimately depends a lot on environment, road and weather conditions.

My first car was a Camaro (V-8 350hp '79 or so). I bought it when I was going to work in New Orleans for a few years. Then I went to grad school in Ithaca NY. I used to joke that it skidded when there was a forecast of snow.

Thanks for this. I was wondering what planet the upper posters were from, extolling the virtues of rear wheel drive -- then I remembered other people don't live in a land where half the year has frozen rain, ice and snow.

Rear wheel drive was great on my '84 Ford Ranger when I needed an excuse to skip school -- couldn't get it up my parent's driveway, sorry!

Meanwhile the janitor who can only afford an RWD pickup makes it to school just fine...

>I really hope they do not make the mistake of making this a front wheel drive car.... etc.

I agree. Furthermore, using an electric motor negates the "packaging" and efficiency advantages of front wheel drive, so it is kind of hard to see why they would... and yet Nissan Leaf (best selling electric car so far) is front wheel drive.

It's because understeer is more desirable in a mass-market car than oversteer. The average driver's natural reaction, which is to quickly lift off the accelerator and jab the brakes, leads to disastrous results in an oversteer situation.

What you are describing is "lift-off oversteer", which is a function of vehicle's weight distribution, and not the rear vs front wheel drive. A desirable mild understeer is easy enough to engineer into a RWD car.

There is also "power-on oversteer" which will occur in a RWD car without suitable control if the road conditions are bad enough, eg. on ice. "Power-on understeer" occurs in FWD cars. The appropriate solution here for both FWD and RWD is electronic stability control (which is pretty much standard at least where I live (Australia)), and particularly easy to implement with electric drive.

Rear wheel drive kills untrained drivers (and their families).

It's not the first time I read in the papers that some poor woman, or man, slammed their rear-wheel drive BMW or Mercedes sideways into a tree or whatever, occasionally killing the child they carried.

That's when I feel like throttling the young bloods who get their jollies drifting around the roundabouts and pooh-poohing front wheel drive cars which are perfectly adequate for 99.9% of the population.

Man, I can't see the day we featherless bipeds aren't allowed to touch the pedals and wheel any longer on public roads.

RWD Hellcats/Corvette/Camaro? Yes. RWD Chevy Bolt's? Probably not.

I'd think that modern traction control on an electric drivetrain with instant response should make it a non-issue. The RWD Model S is fine, for example. You can make the rear end skip a bit if you floor it going around a good curve in the rain, but it takes some effort, and that's a much more powerful car than the Bolt. The Model S P85 can get a little too exciting, but that's a really powerful car.