Subaru AWD vs. other car makers' AWD

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It's an interesting sort of advertisement, using freely available (even if you have to hire the vehicles) information.

Like the Mobil 8x wear adds.

Probably factual, but biased as all get out with stuff that wasn't told (and doesn't really need to be in an add).

and besides, if the front wheels are on ice and the back are on tarmac, it's only 6 or so feet for them all to be on ice...doesn't save much of a walk/tow.
 
Originally Posted By: Throckmorton
Even though this video was made for Subaru salesmen, it's still pretty interesting:

Subaru AWD vs. Competition

See the difference between Subaru AWD and everyone else. Not all AWD systems are created equal.

I am surprised that the CRV or Highlander couldn't transfer enough torque to the back wheels to get them over the hump they had just out of view. The clutch or viscous coupling to the rear must've been smoking hot...
I was surprised how many times the subaru had to turn the front wheels before the "AWD" kicked in, that's not what you want when pushing the limits of traction in snow...

The simplest system would be true AWD with a centre diff driving all 4 wheels all the time and then traction control using the brakes to put power from spinning tires to non spinning tires. All the mechanicals are spinning 100% of the time anyways on the highway with the viscous coupling and centre clutch systems, so I don't see how there would be a significant difference in mileage?

I do like real 4WD as it puts 100% of power to either axle, and even without TC in 4-low you can just drag the brakes yourself at the same time as you give it gas to transfer power from the spinning pair of wheels to the non spinning... I've had to do it the odd time and it makes a difference.
 
can't watch the link here. My 97 legacy used a center diff with limited slip clutchpack. there was no bias, it was 50/50 front/rear under normal conditions, not a FWD with a dragging rear. it was absolutely a hoot in the snow, and very capable. It handled descents far better than our 4wd pathfinder.

we had a 97 AWD crv that was fwd with rear assist. Front had to slip first, but the rear was quick to engage and "bump" the car forward. it was not as graceful, but it did the job. IIRC, volvo and several others were similar.

That legacy was pretty unstoppable until the bumper started to plow. Never had snow tires. (Lived in MD).

But yea, subaru has a number of systems, some more performance biased, some more weather biased. I wished mine had a L range...

Interesting... wife has an MDX. It's "SH-AWD" is FWD with electronically modulated L-R rears, separate L-R modulation, ie, one clutch for each side. If you do a full lock on the rear axle, the bench test spec is that full lock must provide minimum 155 ft/lbs to each tire. That roughly equates to 310 lbs of force from the rear... that's all. Seems very weak... and this is a $40,000, 4,000lb vehicle!!!! Also same system used on the newer pilots, and the ridgeline. Maybe it can increase ft/lb under slippage?

Heck, just with a 50/50 F/R split, a center diff will slam more than 150 ft/lbs of torque to the back axle.

The devil is in the details...

M
 
I too have been impressed with observing Subaru's AWD at slow speeds, like creeping up an ice-covered driveway, but I am more concerned with how well these systems work at high speeds on slippery roads. My own totally unscientific observations here in northern NY indicate that I see a fair number of Subarus, Audis, etc. off the road when things are slippery. Is that because they can accelerate easily to speeds they shouldn't be going? Or is it because something in the AWD makes the cars hard to control at higher speeds on slippery surfaces?
 
AWD helps you to get going, but not to stop. People with AWD that ended up in the ditches were overly confident in the vehicle's abilities.
 
Originally Posted By: Ursae_Majoris
AWD helps you to get going, but not to stop. People with AWD that ended up in the ditches were overly confident in the vehicle's abilities.


That's exactly it. I can't count how many 4x4s I see on the side of the road when it snows b/c of this.

I used to drive through some twisty back roads to work, when it would snow and ice the roads would be bad and yet I'd have 4x4s on my tail who would often swerve around my Subaru to continue on faster than I was willing to go. On several occasions I would catch up to them and pass them simply b/c they were stuck after sliding off the road. And in one case, I came up on the vehicle after it skid into a pole messing up the vehicle fairly bad (vehicle damage only, passengers were all fine).

4 wheel drive get you going, but almost all cars have 4 wheel braking, why 4x4 drivers would think that they can stop significantly better than other cars on snow/ice is beyond me.
 
Originally Posted By: Ursae_Majoris
My Isuzu has a Borg-Warren center differential. In Torque-On-Demand mode, it is normally a 100% rear wheel drive (with LSD), but up to 50% of the torque can be transferred to the front wheels, in 4 Lo, it will lock at a 50/50 split.

Unlike Subaru's AWD, Axiom's system does not have the associated gas penalty.

I've gone thru 2 feet of wet snow, old muddy and rutted logging roads without getting stuck.


Subaru's do not have a fuel penalty. That is conventional wisdom. The EPA ratings of a 2010 Subaru Legacy with 4cylinder are on par with a 2010 Honda Accord and the cars are the same size.

The penalty of AWD is 1-3 MPG in modern vehicles.
 
I have an '04 Legacy 5 speed, with the viscous coupler, lsd in the rear diff, 50/50 split. I just put a new set of Yoko Envigor's on this car last month, I'm pretty eager to see how it does in the snow this year.

Last year, even with tires that were 75% worn, the car did fine. I should rock with the new tires. I also get 30 mpg highway, so the fuel penalty is bunk.
 
sure there is a fuel penalty for AWD in a subaru. I'd bet it's about 1 mpg. If you look in the last years that AWD/4WD was an option, there was a 1 mpg difference right on the sticker. That spinning diff, the t-case, come with some mechanical loss. In their diffs that bias more to the front or rear, like in the sti, it will be more, as more gears are spinning. They use the same hitachi-made rear diff now that they did in the '80s and beyond... you just can't compare apples-to-apples now b/c they don't offer a 2wd car. Is 1 mpg a big difference? Check and see what it costs in a grand cherokee... not that far apart...
 
Originally Posted By: meep
sure there is a fuel penalty for AWD in a subaru. I'd bet it's about 1 mpg. If you look in the last years that AWD/4WD was an option, there was a 1 mpg difference right on the sticker. That spinning diff, the t-case, come with some mechanical loss. In their diffs that bias more to the front or rear, like in the sti, it will be more, as more gears are spinning. They use the same hitachi-made rear diff now that they did in the '80s and beyond... you just can't compare apples-to-apples now b/c they don't offer a 2wd car. Is 1 mpg a big difference? Check and see what it costs in a grand cherokee... not that far apart...

Everything is spinning all the time in almost every recent AWD and 4WD car, its only connected in different ways at different times. Only with true manual hubs (switched at the hub)do axles stop spinning.
If I had perfectly equal sized tires and drove in a straight line there would be no real difference in mileage driving my Tracker in 2WD or 4WD. The front axles and diff spins all the time already, and my Tracker starts spinning up the front driveshaft, as it is old enough for the transfer case to disconnect the front driveshaft when in 2WD, most if not all new vehicles don't bother doing this anymore as the mileage hit isn't significant.
 
My parents have two Outbacks and my partner has an A6 Quatrro Avant. There's no doubt in my mind that the Audi is superior with it's Torsen center diff. It's 60/40 F/R torque split makes it almost as much fun to drive as my RWD 3 series but with a lot more security.

I had a competition with a fellow snowboarder at the hill one day. We wondered whether his Hummer H2 could get farther up the snowboard hill than the A6. Even though the Audi had only all-seasons on it, it was able to get as far as the "[censored]" H2 with its inferior diffs that allowed total stuckage.
 
Originally Posted By: andrewg
Here is a more realistic vid showing just some hill climbs in deep snow with various vehicles (none Subaru).
http://www.youtube.com/watch?v=vAHPMUkhj5Q

Realistic? I don't know about you, but my commute doesn't seem to have any ski hills on it...
That "test" is more about each vehicles ground pressure and power to weight ratio, than its AWD system.
 
Originally Posted By: IndyIan
Originally Posted By: andrewg
Here is a more realistic vid showing just some hill climbs in deep snow with various vehicles (none Subaru).
http://www.youtube.com/watch?v=vAHPMUkhj5Q

Realistic? I don't know about you, but my commute doesn't seem to have any ski hills on it...
That "test" is more about each vehicles ground pressure and power to weight ratio, than its AWD system.

Realistic as opposed to the Subaru video. Real snow....real hill....then try and climb it. Can't get any more real than that. Everyday winter driving and icy road conditions? No. But I HAVE been in deep snow and tried to climb a hill before. Maybe you've never been up a REAL mountain pass out west?
 
I briefly glanced through the video. Can't speak to the vehicles tested. I will say I think it was a very limited sample in the test field.

I had an 08 Chevy Equinox( AWD ) with Firestone Destination LE tires. It was like a little tank in the snow. I guess you would call it an auto or part time AWD system as it came on by itself when wheels slippage occured. FWD when not engaged. Driver had no control over it( only part I disliked ).

Had it out in some god awful winter conditions and storms and it went through it all with ease. To actually get it to slip I had to purposely push it beyond what was safe. IT wasn't a 4WD truck but it was darn good.
 
Originally Posted By: andrewg
Originally Posted By: IndyIan
Originally Posted By: andrewg
Here is a more realistic vid showing just some hill climbs in deep snow with various vehicles (none Subaru).
http://www.youtube.com/watch?v=vAHPMUkhj5Q

Realistic? I don't know about you, but my commute doesn't seem to have any ski hills on it...
That "test" is more about each vehicles ground pressure and power to weight ratio, than its AWD system.

Realistic as opposed to the Subaru video. Real snow....real hill....then try and climb it. Can't get any more real than that. Everyday winter driving and icy road conditions? No. But I HAVE been in deep snow and tried to climb a hill before. Maybe you've never been up a REAL mountain pass out west?

Nope, never done a rocky mountain pass in the winter, but 8 or 12" of snow on pavement on a sustained 8 or 10% grade is something quite different than a groomed ski hill...
My driveway has a couple hundred yards of 8-10% grade and a bend at the bottom which prevents a pure momentum approach, so I do know a thing or two about winter traction, if I don't get up there I've got a 1/4 mile walk so I pay attention to what works for me and what doesn't, and I'm in no hurry to get any particular vehicle based on those videos...
Neither of the video tests really showed anything like my driveway or normal winter driving so while they are interesting, they don't really show or prove anything. And what works best at low speeds (all 4 tires locked, 100% power available to any tire all the time) isn't ideal at higher speeds.
 
Originally Posted By: IndyIan
Originally Posted By: meep
sure there is a fuel penalty for AWD in a subaru. I'd bet it's about 1 mpg. If you look in the last years that AWD/4WD was an option, there was a 1 mpg difference right on the sticker. That spinning diff, the t-case, come with some mechanical loss. In their diffs that bias more to the front or rear, like in the sti, it will be more, as more gears are spinning. They use the same hitachi-made rear diff now that they did in the '80s and beyond... you just can't compare apples-to-apples now b/c they don't offer a 2wd car. Is 1 mpg a big difference? Check and see what it costs in a grand cherokee... not that far apart...

Everything is spinning all the time in almost every recent AWD and 4WD car, its only connected in different ways at different times. Only with true manual hubs (switched at the hub)do axles stop spinning.
If I had perfectly equal sized tires and drove in a straight line there would be no real difference in mileage driving my Tracker in 2WD or 4WD. The front axles and diff spins all the time already, and my Tracker starts spinning up the front driveshaft, as it is old enough for the transfer case to disconnect the front driveshaft when in 2WD, most if not all new vehicles don't bother doing this anymore as the mileage hit isn't significant.


I think you missed my point. earlier post claims there is no penalty for the extra AWD hardware when compared to a fwd accord. If that extra stuff is removed, as in comparing an awd subie to a fwd accord, there IS a difference.

I put manual hubs on a 97 pathfinder, which spun all things all the time as you mention. immediate 1 mpg difference, driving 400miles/week, paid for themselves in 6 months at the time. You could even feel it in the steering wheel when the axles were disconnected. And it was a standard 2 hi, 4 hi, 4 lo t-case.

can't argue with physics. more stuff to turn requires more energy.
 
Last edited:
Originally Posted By: Kitto
Can the traction control on the Toyota and Honda be turned off? And will it make a difference?


Yes the VSA (or VSC I forget what Honda calls it) on my 07 and 08 CR-Vs can be turned off. I think it would be useful for times when you want the tires to spin in deep snow to help get through, but frankly I have never needed to turn it off. Even after 10" of snow falls I have no problem getting out of my driveway and off of my street before the plows make it by.
 
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