I have had many arguments with SUV lovers who think that AWD is the ultimate life saver and makes their car a whole lot safer. That of course is complete nonsense - SUVs are not only dangerous, they are very difficult to control. My argument has always been AWD only helps you when you are accelerating; when it comes to braking, turning and emergency maneuvers, AWD is just extra heavy junk that only makes the car turn worse and the stopping distances longer.

But recently I have heard people say that in some advanced awd performance cars, the awd system does work most of the time. For example the STi, the Evo and a few others. So the question is, does awd in high performance cars (and SUVs too for that matter) do anything positive during turning and emergency maneuvering or is it only beneficial for acceleration? I am guessing in some cases engine braking with all 4 wheels can be positive, but probably makes you understeer more than anything.

 

I think this system from Acura is working all the time
From the Acura site: "Super Handling All-Wheel Drive™ (SH-AWD™)--the groundbreaking all-wheel drive platform that distributes torque between the front and rear wheels and can send up to 100% of the rear-wheel torque to either the left or right rear wheel."
I think the Subaru system works in a similar fashion.

 

Are you talking to people who actually have AWD, not part-time 4WD? My AWD car ('88 323 GTX) has enhanced performance due to being able to put power to the ground that would normally just turn front tires into smoke. In an SUV it allows you to get out of snow or mud better (under acceleration) but nothing really in emergency situations or braking. For most SUV drivers it just makes them drive way over their heads with the mistaken notion that they are "safe".

 

I've got an Audi A4 Quattro (awd) and it's a full time system. I feel the awd system makes the car handle better in regular driving, in many conditions, then a FWD car. My previous car was a 95 Mits. Eclipse GST (210hp, FWD). If it was humid outside the GST would spin it's wheels easily, it could be a challenge to drive in bad weather (had fun doing it, since I love a challenge).

Ofcourse traction control and stability management makes many FWD cars handle very well too. The GST had neither of those.

Some nice things about the AWD system is four wheel engine braking, zero wheel spin in rain conditions (however the A4 is a little underpowered based on it's weight). Let me tell you tho, it's a kick in the pants to drive in the snow

That being said, it's the TIRES that make a difference in snow conditions more than the drive system. Snow tires on a FWD car are probably better/safer/more fun then cheap/bald/the wrong tires on an AWD system.

If you're talking about a SUV, there are a lot of diffs in the systems they use. Some are FWD until they slip, then go into AWD, some are RWD until they slip. Some are 4x4 where you can't put them into 4x4 mode when there is wheel slip (dirt, snow, mud, heavy rain) or you will damage the system. That doesn't include the low-range systems that are really designed for off road.

 

Dolmangar, is correct. There are many different systems available out there and they are NOT all created equal. In terms of safety, a good AWD system will definitely offer additional safety when cornering and emergency maneuvers. The worse the conditions the bigger the advantage of AWD.

The systems on Audi and Subaru are two of the best. Some of the more recent converts to AWD use electronic switching to control the three differentials and depending upon the software engineer (think Seimans and the MINI ECU fuel delivery problems) determines the value of their AWD.

The inherant mass of an SUV immediately puts it at a disadvantage in any emergency maneuver. Their center of gravity is higher than any passenger car making them more prone to roll-over. Their weight makes for longer emergency stops. Watch your backs when you have to stop qiuckly, just because you can stop safely does not mean the big lumbering SUV can.

AWD does not effect braking. AWD does not change the laws of physics. If there is poor traction you might be able to get going with AWD, but you might not be able to turn or stop. Look along the side of the highways when you are headed for some skiing, it is mostly SUVs off the road burried in the snow banks.

Talking about tires, I'll take a front engined rear wheel drive car with propper snow tires over any AWD with marginal tires, thank you very much.

 

I guess I didn't state my question clearly enough. What I am most interested in is does the awd system do anything at all when the gas pedal is not being used. My attitude has always been that if my foot is not touching the gas pedal then the awd is completely irrelevant and just becomes extra weight for the car.

But i have been hearing people say that the high performance, computer controller awd systems do more than that - almost acting like DSC in some cases. Thats what the question is.

As far as the lack of traction and the overall danger of SUVs, I am well aware. My wife had a Mitsibishi Montero that she purchased before marriage. I had her get rid of the car promptly. The reason? We would actually intentially drive the MINI in the snow, because it felt much safer than the Montero. And the Montero did have a very nice AWD system. She now has a 4wd Toyota Matrix with Blizzak snow tires for the winter. The matrix is smaller, lighter and more nimble and with the snow tires on, it is a snowmobile. Even with a pretty crappy 4wd system i can mash the gas pedal in the snow and the car takes off as if there is no snow on the ground.

 

No drive system (FWD, RWD, AWD, 4WD) will make any difference to anything other than putting the torque from the engine on the ground. It will affect acceleration and (engine) braking, but not much else.

There will be a difference in cornering, but that comes from shifting torque from the wheel that is slipping to the wheel with grip, much like LSD. Now, I will say that I've driven the crap out of my car, and I don't have LSD, and I've never felt like I was losing power in a turn that could have been restored by transferring torque. I'm not a professional race-car driver.

An AWD system will get you off the line quickly; after that, it's just another drive-train.

 

I used to drive a Subaru 2.5RS (kinda like a non-turbocharged little brother to the WRX), and developed the ability to induce oversteer or understeer pretty much at will using the throttle, so I adamantly contradict those stating that AWD only helps off the line! This is a clear benefit during cornering.

Since your question seems to be related mainly to braking conditions, I'll add that *some* AWD systems are active even when no throttle is applied, and these at least, can help distribute the braking forces among the wheels. My old '89 Honda Civic wagon had "Real-Time" All-Wheel Drive that specifically provided this benefit.

I was such a fan of AWD, that it *almost* prevented me from getting a MINI, but several test drives convinced me I wouldn't be missing it (at least for a while...)

I also would like to point out that AWD is very different from 4WD... I also owned a Jeep Wrangler, and that was the first car that I ever spun - POS!

_Dave_

PS: Oh yeah, I forgot to mention that all of this is under DRY conditions. Some folks think AWD is just for bad weather, but I'm here to tell you it *does* make a difference under normal (highly spririted) driving conditions.

 

Instead of being lazy, why don't you go to the auto manufacturer's web sites and do some research on how the various systems work.

As to what you know about AWD or 4WD, feel free to remain ignorant and superstitious about them. Just because a POC like the Mitsubishi handles poorly in snow does not mean all systems or vehicles are the same.

I guess AWD sucks, which is why the world rally cars use it.

You're talking out your *** as to the efficacy of these systems.

 

And I would argue that distributed braking is not technically a part of the AWD system. It's about taking the power the engine is producing, and distributing it to the wheels. Braking systems are quite the opposite, and that system operates entirely at the wheels.

I agree that AWD can (and does) help in very aggressive cornering, but if you're inducing oversteer, you're defeating the advantage of AWD: keeping power to a wheel that has traction. At that point, you're just "hanging tail", and we can do that quite happily in our FWD Coopers.

I realize this argument is more complicated than I'm making it seem, but I want to re-iterate that braking is not properly part of a power-train.

 

Is it the moderator's job to take away accounts from people who have mental problems? Lets see, without any provocation I was called LAZY, IGNORANT and SUPERSTITIOUS and TALKING OUT OF MY ***.

Dude,
a) take it easy
b) i have read, and i still have questions, hence my post
c) learn how to read yourself
d) prozac

I never said AWD sucks. AWD is great and if you read my post about the Evo, all i do is praise it, and the Evo arguably doesn't have a great awd system either. So I have NO CLUE where you got that I think AWD sucks. Again, mental issues?

Second, the late 90s Mitsubishi Montero, when it was made boasted a really nice AWD system and even by today's standards that system is considered pretty darn good. At very slow speeds, the car was crazy, i even used it to drive up and down a steep driveway with 2 feet of snow on it to pack the driveway down enough to get my MINI out. My problem with the Mitsubishi and this has nothing to do with the Mitsu's or any other car's AWD system is that it was freaking heavy and had major problems coming to a stop in the snow once going fast enough. It also handled terribly because of its mass in the snow. In those two departments, the MINI was safer + the DSC which kept the MINI pointed in the right direction. My comparison of the 4WD Matrix to the AWD was not to say that 4wd and awd are the same. As a matter of fact at some point i think i called the 4wd system on the matrix mediocre or something. What I was getting at there is that even with an inferior 4wd system, the matrix is a much better snow machine because of the snow tires and much lighter weight.

Once again pscycho: LEARN HOW TO READ and TAKE PROZAC.

 

Thank you. I took some Prozac and now feel better.

 

My Mini is the first vehicle I have purchased in years that does not have AWD. I find it to be much safer in the snow and rain. I would not want my wife to drive anything other then AWD. Some systems are obviously more advanced then others though. I also have had no real problems stopping cars in the snow due to added weight. One of your statements is that the awd system is not doing anything when you don't have your foot on the brake. That is obvious but that is not the purpose of AWD. (Although your foot is on the gas most of the time I would hope or you would not get anywhere)


Currently owned full time AWD:
VW Passat w/4-motion
Land Rover Discovery

Past owned full time AWD:
Eagle Talon TSI

 

I just like the extra edge on the handling awd provides. We had an Audi S6, and the car handled awesome.

For the smart a...s comments, please entertain yourself with other thing. Stupid

 

If the AWD system is only useful when accelerating, what makes it that much safer in the snow over a fwd car? When I think safety in vehicle dynamics, 90% of that safety in my mind comes in braking and turning and 10% in the power to get yourself out of a dangerous situation. Maybe that mix is a little bit different in the snow, but still, the key is to be able to stop well in snow and turn without spinning out. I think AWD is very useful with getting yourself up steep snow covered hills, getting out of deep snow and in, some limited cases, getting yourself out of another car's way. But still, the biggest part of safety in snow comes from good braking distances and stable, safe handling - where the AWD/4WD system plays no part. And this is not criticism of anyone who has and loves awd systems, as I myself bought a 4wd Matrix vs a fwd Matrix.

Too many SUV drivers think that their car is actually safer in the snow because they have AWD. SUVs weight 2 times as much as the mini and require a their tires require a lot of traction to brake and turn that mass - the traction that is very very limited in the snow.

 

So would you say that a FWD SUV is safer than a AWD SUV just because of the couple hundred pounds that the AWD system may weigh? Or are you arguing that SUV's in general are unsafe? I am not sure that the comparison between a 2500lb Mini and a 3500-4000lb SUV is a fair comparison. They are completly different vehicles and different benefits. My Land Rover is much more capable of going places that the Mini cannot and can haul and tow things that the Mini cannot. That doesn't necessarily make it better just different.

As for Snow I will be using my Mini w/Blizzaks because I have a 1 hour commute but around town I will be in the Rover. Reason...very few snow drifts that I can't get out of or over in it. Seems like a better idea to me.

By the way, ALL VEHICLES ARE DANGEROUS IN SNOW AND ICE. You have to be careful no matter what you drive.

 

Not just when accelerating, but whenever your foot is on the gas. Going in a straight line and maintaining speed, you're still putting engine-power on the ground. Recognizing that turning is technically accelerating, I would also say that AWD/4WD is very useful when just turning, and could certainly save your butt on snow / ice. AWD is transferring torque to the wheel with traction, and 4WD is turning all four wheels at the same speed. Obviously both are useful on treacherous surfaces.

 

Thats a good point. I didn't think of that.

On the other hand there is probably no FWD production car in the world that will cause you to oversteer when your foot is on the gas. When going 30mph and maintaining that speed in the snow, there is so little power being sent to the wheels that I would think the gains in safety and straight line stability from AWD are not that huge. When making sharper turns and accelerating out of a snow turn, I can see the benefit.

About 5 years ago, i read an interesting article in Car and Driver about snow driving with AWD, FWD and RWD. They took a bunch of very similar luxury family sedans (Mercedes E class i think) and did some real world snow driving testing. For the FWD test they had to use another car of course. If i remember correctly, here is how it track times stacked up:

1) AWD with snow tires
2) RWD with snow tires
3) FWD with snow tires
4) AWD with all seasons
5) FWD with all seasons
6) RWD with all seasons

Car and Driver noted that AWD/RWD/FWD didn't matter - what mattered snow tires and dynamic stability control. Therefore I am confident that the MINI on snow tires and DSC (which I have) is a far SAFER snow car than most SUVs that was driven off the lot in the last few years. I know too many people with WRXs and crappy RE92 bridgestone tires that crashed their cars in the snow. A WRX with quality snow tires and DSC - now that, would be snow driving heaven!

 

Snow-driving heaven is getting to about 15mph, pulling the e-brake, and turning the wheel slightly. Sling through a nice 180, release the e-brake, turn the wheel the other way, and drive on. I spent a lot of time doing that last Winter. I even got pretty good at doing it within 2 lanes.

I find it hard to believe that RWD / FWD makes no significant difference. When I had my Jetta and my wife had her Volvo, we had a major snowstorm. There is a hump-back bridge that you have to use to get into our neighborhood, and she couldn't get across it. I had no problems with it. Granted, the Volvo was heavier, but the front end of her car just shot around like a frightened chicken.

Why can't the Swedes make a car that's safe IN THE SNOW???

 

I think RWD vs. FWD makes a difference when you don't have snow tires and you don't have traction control or dynamic stability control. Just about every rear wheel drive car today has some kind of traction/stability control, which is kinda sad actually - people buy 400hp rear wheel drive cars but don't actually know how to use them, so they need traction control to help out. Those same people take their 400hp rwd cars shod with performance summer tires and try to drive home in the snow - idiots.

And even traction control and DSC won't really safe you that much in the snow. Some people think the DSC is the absolute life saver but they don't understand that if you go into a turn really fast, and there is not enough traction available, it doesn't matter - dsc only controls the direction of your car, not the speed. If the 4 tires, as a group, don't have the combined traction to handle the lateral acceleration of the car, dsc won't help.

I need to play around in the snow too - this winter I will seak out an empty snowy parking lot and start messing around. So far, in my experience, DSC has been a great help in keeping the car pointed in the right direction. I want to turn it off and start doing 360s.

 

I don't think that's exactly true. I'm pretty sure I've read that DSC uses "intelligent" braking to help control your direction.

I think if you try to oversteer, DSC will engage, restrict the turn, and apply brakes to the wheel(s) with the most traction to keep your butt on the road.

I don't have it, so I can't attest to that, but I'm fairly confident that's how it works.

 

Of course, the DSC uses brakes - its the only way you can control the direction of the car. In all my experience in playing in an empty snowy or rainy parking lot DSC selectively applies brake pressure to specific wheels to correct heavy understeer and any hint of oversteer. Its kinda cool to hear the DSC kick in, even with my foot on the gas pedal i start hearing what sounds like ABS coming from different corners of the car. As soon as the car is pointed in the right direction and any overesteer has been cured, the DSC stops and lets the car coast. There is probably someone out there that can elaborate a lot more on the system. I will try to read up on it today.

That said, DSC is useless if you badly overcook the turn. If the forces required to make a turn are greater than what the tires can handle, it doesn't matter whether the DSC transfers weight and energy to one tire or another, the car as a whole will still continue to go wide and fly off the road. DSC will however help with keeping the car pointed, as much as possible, in the direction of the steering wheel, so in theory the car will slowly understeer wide instead of spinning out. (of course its virtually impossible to spin a stock MINI in anything other than snow)

 

Ah, you've not heard my tale...

 

Please.... I know many Itty bitty MINI owners hate SUVs but please.

When that big old Ford Expedition hits that little itty bitty MINI .... well, the laws of physics aren't likely to change ... who get crushed?

OH yeah, you talkind AWD. Modern AWD is on all the time distributing the power wherever needed to each wheel. Hmm, is that better than 2 wheel drive

 

That depends. Clearly there are cars that do just fine while only putting power to two wheels, so you have to define "better". Are you wildly flinging your car around auto-x circuits? Are you driving too fast on snow? If you're driving to and from work, with the occasional fun run through a windy road, I'd say you wouldn't gain much at all from anything more than 2WD, and some of the fun tricks that we can do are all but impossible with AWD and 4WD.

You get the drive-train you need to meet your requirements. It's that simple. If 2WD weren't safe, the US gov't would have made it illegal by now.