Author Topic: 4 wheel drive: a safety feature? (Read 5000 times)

21Rouge · « **on:** August 23, 2008, 12:31:00 pm »

We will be likely purchasing an Outlook/Acadia/Traverse in 2009. Should one consider the AWD option as a safety option just like airbags or ABS? We live in the GTorontoA so it definitely isnt a necessity but I just wonder if it still makes the vehicle safer.

Trainman · « **Reply #1 on:** August 23, 2008, 12:37:23 pm »

If it does make a vehicle safer, wonder how to explain the number of SUV's and pickups in the ditches on our local highways in the winter

More driver care (drive to conditions) and tire choice in my opinion. We could have got the Sienna as AWD but elected not to. And we have no regrets.

If the conditions are so bad you feel you need 4wd/AWD, should you even be driving?

ktm525 · « **Reply #2 on:** August 23, 2008, 12:49:40 pm »

Quote from: Trainman on August 23, 2008, 12:37:23 pm

If it does make a vehicle safer, wonder how to explain the number of SUV's and pickups in the ditches on our local highways in the winter

More driver care (drive to conditions) and tire choice in my opinion. We could have got the Sienna as AWD but elected not to. And we have no regrets.

If the conditions are so bad you feel you need 4wd/AWD, should you even be driving?

#1 is easy = higher center of gravity.

The safest option would be AWD and proper tire choice. Never can have too much traction IMO. AWD just might help you get out of the way when some out of control vehcle is careening down an icy/snowy slope towards your new car...

safristi · « **Reply #3 on:** August 23, 2008, 01:04:17 pm »

..that's why God gave us 4_skins.........................

21Rouge · « **Reply #4 on:** August 23, 2008, 01:45:39 pm »

Quote from: Trainman on August 23, 2008, 12:37:23 pm

If the conditions are so bad you feel you need 4wd/AWD, should you even be driving?

Hey thats not fair

. You are making quite an extrapolation re my original inquiry.

Heck if condtions are so bad you feel you need brakes,....

I was only wondering, all else being equal (i.e same good winter tires, same speeds,....), does AWD help make a vehicle safer...even if it was just rain?

Leviathan · « **Reply #5 on:** August 23, 2008, 01:59:55 pm »

I think so. We don't get a whole lotta snow in Vancouver but AWD sure helps when merging into traffic, left turns with on coming traffic etc during the rainy season.

tpl · « **Reply #6 on:** August 23, 2008, 02:07:52 pm »

"proper" AWD, that is all 4 wheels driven all the time with some device to apportion torque front/rear and ideally left right as well such as: Audi Quattro, Subaru, BMW and M-B AWD systems, Land Rover, Porsche as well IIRC... there may be others.
'Proper" AWD must be capable of being used under all conditions as distinct from 4WD which usually cannot be used at speed on the highway.

but NOT slip and grip Haldex cars.

Will give more acceleration traction on slippery surfaces but can INCREASE 0-60 times on good surfaces as there may be more traction than the engine power can use.
Will ALTER but not necessarily improve cornering most of the time and, in conjunction with appropriate tires for the season, improve it quite a bit in snow and ice.

It will worsen fuel economy.... mechanical drag and more weight.
It can indeed make you overconfident that you have more grip than you do. Hence Trainman's comment.

In TO a bigger contribution to winter safety would be 4 top quality winter tires

I owned two AWD cars over the last 8 years each with snow tires. Never came anywhere near an unsafe moment while commuting every day.

ktm525 · « **Reply #7 on:** August 23, 2008, 07:21:57 pm »

Quote from: tpl on August 23, 2008, 02:07:52 pm

"proper" AWD, that is all 4 wheels driven all the time with some device to apportion torque front/rear and ideally left right as well such as: Audi Quattro, Subaru, BMW and M-B AWD systems, Land Rover, Porsche as well IIRC... there may be others.
'Proper" AWD must be capable of being used under all conditions as distinct from 4WD which usually cannot be used at speed on the highway.

but NOT slip and grip Haldex cars.

Hey dems fighting words. The latest Haldex systems are impressive. Instantaneous traction, not "slip and grip" Exactly how many newer Haldex equipped cars have you driven in poor conditions?

Leviathan · « **Reply #8 on:** August 23, 2008, 08:33:34 pm »

I don't know who supplies the system in the Tribute/Escape but it does work very well. But is it "proper"? Don't care because in snow or rain the car simply moves forward without slipping

If anyone cares, the press release says:

Quote

Car-like front-wheel drive is standard. If extra traction is necessary – either for off-road driving or pulling heavy loads in slippery conditions – the Tribute is available with Mazda’s innovative Active Torque Control Coupling (ATCC) four-wheel-drive system. This ingenious system is available with both four-cylinder and V6 engines and automatic or manual transmissions.

A sophisticated computer monitors the engine, wheel speeds and transmission, and automatically transfers torque between the front or rear wheels. The split varies between zero and 100-percent. It senses where traction is strongest and delivers the appropriate amount of torque for optimal grip. Unlike mechanical systems, which react only to wheel slip, ATCC predicts wheel spin, and prevents it from happening in the first place. It changes continually, to suit ever-changing driving conditions, and is also completely automatic, so no driver settings or adjustment is necessary. It reacts faster than a hydraulic system because there is no lag time waiting for a viscous fluid to heat up before splitting power between the axles. The system is also useful on road – such as in snow or heavy rain, or any time where there is a potential for loss of traction. Compared with less sophisticated four-wheel drive systems, ATCC improves driving responsiveness, handling and fuel economy.

tpl · « **Reply #9 on:** August 23, 2008, 09:03:53 pm »

Quote from: ktm525 on August 23, 2008, 07:21:57 pm

Quote from: tpl on August 23, 2008, 02:07:52 pm
"proper" AWD, that is all 4 wheels driven all the time with some device to apportion torque front/rear and ideally left right as well such as: Audi Quattro, Subaru, BMW and M-B AWD systems, Land Rover, Porsche as well IIRC... there may be others.
'Proper" AWD must be capable of being used under all conditions as distinct from 4WD which usually cannot be used at speed on the highway.

but NOT slip and grip Haldex cars.

Hey dems fighting words. The latest Haldex systems are impressive. Instantaneous traction, not "slip and grip" Exactly how many newer Haldex equipped cars have you driven in poor conditions?

none. Just hearsay. if you say they are good now I'll believe you BUT they are not delivering torque to all the wheels all the time which makes them not real AWD.

The same must apply to any system such as the ATCC although I imagine that the ATCC system could be engineered to always deliver some torque everywhere.

ktm525 · « **Reply #10 on:** August 23, 2008, 11:05:08 pm »

I forgot to add that while AWD gives you traction it also tends to take away steering feel.

tpl · « **Reply #11 on:** August 24, 2008, 05:56:19 am »

Quote from: ktm525 on August 23, 2008, 11:05:08 pm

I forgot to add that while AWD gives you traction it also tends to take away steering feel.

I agree with that to a certain extent.... but no more than many FWD cars.

Rupert · « **Reply #12 on:** August 24, 2008, 08:13:27 pm »

AWD gives more traction I suppose but I have not read here that it stops your car any quicker and in fact it does not I think. Have not read that stearing is any better with AWD and one comment seems to indicate not so. So unless the occasion occurs that you have to get out of the way of a careening car it would seem to indicate that tires are the answer for best safety in the winter. If bad snow or icy roads are the norm for you maybe the extra traction of AWD will help to get moving but not to stop. AWD could then be considered a safety feature in an emergency.
I am not a fan of AWD. It's more complicated and uses more fuel and possibly gives a false impression of grip. hence the remark about SUVs in the ditch. I prefer to keep it simple. However front wheel driven cars are better than rear wheel drive ones for traction IMO.

Snowman · « **Reply #13 on:** August 24, 2008, 09:00:00 pm »

The advantages of a full time awd system far outweigh the minimal increase in fuel costs IMO. Even my wife will never go back to a fwd or part time awd system. In the hands of a sensible driver the awd advantage in poor driving conditions are priceless.

Rupert · « **Reply #14 on:** August 25, 2008, 07:36:15 am »

Given the fact that you have managed to get going, how so is this a safety issue. Noting the points already outlined. It is to be considered though, that AWD seems to be very popular in more hilly country areas for obvious reasons. Maybe areas of greater winter precipitation. As stated on this forum before, you see a lot of Subarus in New Brunswick. FWD is far removed from the days of predominantly RWD when the drive wheels were not under the engine weight. It's a personal choice and maybe other factors are important too. For instance older drivers may value the the ability to get going without having to dig or push. Heart attacks have been known to occur doing this.
I had an occasional 4WD Trooper in the Toronto area, early 90s, and my experience was that it was only needed a couple of times in the 10 years that I owned it. Even though the the rear wheels were driven normally. Since FWD vehicles have way more traction than RWD, you have to weigh the value of paying the extra original cost and fuel costs and extra complexity to go wrong, of AWD consdering it's marginal requirement for many IMO.

ktm525 · « **Reply #15 on:** August 25, 2008, 11:02:43 am »

Quote from: Snowman on August 24, 2008, 09:00:00 pm

The advantages of a full time awd system far outweigh the minimal increase in fuel costs IMO. Even my wife will never go back to a fwd or part time awd system. In the hands of a sensible driver the awd advantage in poor driving conditions are priceless.

Fun as heck too!

tenpenny · « **Reply #16 on:** August 25, 2008, 11:32:02 am »

Obviously, AWD does improve traction and therefore does make the vehicle safer.

Whether it's of much practical benefit in the GTA would depend on how much driving you do in bad weather.

Furthermore, some studies have shown that the safer the car is, the riskier drivers' behaviours become, so the net benefit is never as great as predicted. (Just finished reading 'Traffic', as mentioned elsewhere). So, for maximum safety, only drive an older, unsafe vehicle, slowly, in unfamiliar areas, where you will be on maximum 'high alert'.

21Rouge · « **Reply #17 on:** August 25, 2008, 11:36:52 am »

Quote from: tenpenny on August 25, 2008, 11:32:02 am

So, for maximum safety, only drive an older, unsafe vehicle, slowly, in unfamiliar areas, where you will be on maximum 'high alert'.

carcrazy · « **Reply #18 on:** August 25, 2008, 11:50:52 am »

In some vehicles, like the 07 Outlander 4WD for instance, stability control, traction control and 4WD system are all integrated under one system - ASC (Active Stability Control). So yes, the 4WD system could be a safety feature.
I'm sure other modern vehicles are designed the same way.

johngenx · « **Reply #19 on:** August 25, 2008, 12:06:08 pm »

I'm an AWD fan, as our repeated Subaru ownership will attest. However, it's still all about tires. When we bought our Forester, snow tires were sold out for the winter and it actually had to sit for quite some time on it's POS all-season tires, waiting for the snow to melt. The C230, with it's RWD, no traction control and no LSD (essentially a one-wheel-drive RWD car) would literally run away from the Forester thanks to the MB's winter tires.

1. Driver's brain. Drive defensively and pay attention to conditions. I bet 95% of collisions are just due to stupid driving.
2. Tires. The right tires for the conditions.
3. AWD/ASR/ESP/etc/etc/etc/