: 2010+ SRX4 all-wheel drive (AWD) system: How would you rate it?



RAB
08-13-11, 12:29 PM
I'm thinking about ordering a 2012 SRX4 Premium later this year.. that is, if/when GM decide to make a white paint color available once again for the model.
I'm curious about the all-wheel drive (AWD) system on the 2010+ SRX4. How would owners of 2010+ Cadillac SRX4's rate its AWD system? Has anyone ever got stuck in mud, snow or on ice with their SRX4? Has anyone needed to switch to winter tires on their SRX4 to negotiate the worst of winter in their area of the country?

It's clear that AWD systems are not all created equal. Check out these 2 videos on YouTube:
Video 1: http://www.youtube.com/watch?v=HvqQuC_8VrM
Video 2: http://www.youtube.com/watch?v=U-FoUTPja4Y&feature=related

The Audi Q5 - which is equipped with Audi's fabled Quattro system and is the highest rated compact sporty SUV/Crossover according to Consumer Reports as well as several automotive publications - fails miserably in the featured tests, which simulate 2 tires (video 1) or 3 tires (video 2) sitting on glare ice.
I wonder how the 2010+ SRX4's "advanced AWD system" (*) would perform in these particular tests.

* Link to GM Media's description of the 2010+ SRX Advanced AWD System:
http://media.gm.com/content/media/us/en/cadillac/news.detail.html/content/Pages/news/us/en/2009/Feb/0224_CadillacAWD

Kuya
08-14-11, 04:59 PM
In May, I purchased a 2010 Premium (white) AWD SRX. . .

I purchased it used with 15kmi and have loved every minute of it, for the last 3 months. I live in upstate New York and we get some pretty harsh winters. I don't plan on going out to get winter tires for the SRX, as I have never done so with any other vehicles I have owned. And this is my first AWD.

I have yet to get stuck in mud or drive in the snow (this will be my first winter with the SRX) - BUT . . I have felt the AWD kick in when needed. Driving on wet roads, in the middle of a downpour where you can barely see the car in front of you is a BREEZE. No complaints whatsoever there. Best vehicle I have ever driven in rain/wet roads.

My parents driveway is a very steep hill going from the road downward to the house, and t is a gravel driveway. My previous cars would have a little issue on that hill. Not that they could not manage to get up out of the driveway . . . but the tires would often struggle to find solid grip on the loose gravel coming up the hill. The SRX shows no signs of slippage or tire spin coming out of the hill.

Being 4500 + pounds, in weight and (so far) great AWD . . . I welcome Old Man Winter this year!

Be patient on the white . . it is a HEAD Turner for sure. I love the plat ice and am glad I got one of the few on the market out there. Black was my first choice in color . . until I saw the white one in person . . the white with the chrome is super nice.

Good luck

TheCaptain
08-14-11, 11:12 PM
Hey RAB, i've used the SRX's AWD system with and without Stabilitrack in the winter, and in the mud (ST on) and it works awesomely! Never worry about getting stuck again (almost, its not 100% stuck-proof, lol) You can wail this thing around a slick corner on full ice and it launches, rear wheels sliding out first under heavy throttle, then adjusts torque towards the front and back-forth until you are gone! (Which doesn't take long, its just sweet to feel it kick out the rear wheels, then transfer up front to straighten out) Mind you i ALWAYS turn of Traction Control in the winter because its such a pain on ice and heavy snow, and ST still can stay on with TC off, so you're mucho safe-o.
Also, i let a couple of tires lean into the ditch at highway speed in the winter (mainly because i couldn't see where the shoulder was) and ST brought me back in line pronto like and kicked the cruise off. Such an awesome system!

AND with ST and TC off, you can rally race it however you want! Floor it and kick the rear end out, steer, and soon you'll be slideways before the AWD brings torque back around again! LOTS of fun! :D

jcarlilesiu
08-16-11, 11:34 AM
I used to have the BMW X3 with X-drive and can say that the GM system works just as well.

RAB
08-18-11, 09:07 PM
Hey guys - thank you much for adding your comment.
I think we can all agree that the engineers at GM have designed a great AWD system on the 2nd gen SRX as well as the 2nd gen CTS.
I sent an email recently to a long-time engineer friend of mine who works at GM. I asked his thoughts about AWD systems in general, the video links I included above and how GM's current AWD systems (eg. applied to the Cadillac SRX4 and CTS4) would negotiate the tests in the videos. His comments/insight into this particular area were excellent. I've pasted-in his comments below, and I encourage everyone here to read it. Great stuff. GM have some very talented people on their staff.

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Hi RAB,

Where to start? I could write a book.
First off there are dozens of AWD/4WD systems in the market today, and you are correct in that most are not explained in detail to customers.
Performance based vehicles are generally rear wheel drive based for weight biasing to excel at handling. These types of vehicles use a transfer case to route power to the front wheels.
Non performance based vehicles are generally front wheel drive based where handling is not critical. These types of vehicles use a rear drive module (RDM) to transfer power from the rear propshaft to the rear wheels. [Power from the engine/transmission to the rear propshaft is done by a power take-off unit (PTU)].

I've seen the videos you sent as well as some by various manufacturers. Each has a different philosophy on how AWD/4WD should perform, and the capabilities it should have. For instance many German AWD systems are transfer case-based and designed for purely on-road performance. We've witnessed many different designs throughout the years from different manufacturers.

In general, and in my opinion, the systems of our European counterparts have become less complex.. and less capable. By that I mean they've migrated away from electronically controlled transfer cases to purely mechanical units that use Torsen-biased couplings or open center differentials. Not sure how familiar you are with those terms, but Torsen-biased means there's a coupling in the transfer case that has frictional capabilities that are pre-set to a particular ratio by a manufacturer to inherently transfer more torque to one axle than another. These are cheaper than electronically controlled units but still fairly expensive, and hence the reason many are moving to a purely open center differential transfer case - which is essentially a box with a fixed torque split, no electronics, and far less complex in terms of development and integrating with other vehicle systems. This is exactly what you've seen in the videos and the reasons these vehicles can't pull themselves off of the rollers. When you have an open center differential all of the power will go to the wheel with the lowest traction. To prevent a vehicle from getting stuck, manufacturers rely on the brakes to stop the slipping wheels and send power to the wheel with the most traction. This is called brake-based traction control. Is it effective? Yes - for most drivers it's quite effective. Is it ideal in snow and ice? Far from it. Obviously when the brakes are applied to a slipping wheel you are absorbing engine power and in many instances the engine controls are designed to reduce power depending on how the controls are implemented. You'll notice that in the demonstrations the driver is only applying the throttle lightly, on purpose, to highlight the system short comings. Many of these open center differential transfer case systems are calibrated such that if the throttle is applied hard enough the brakes will typically clamp down hard enough to minimize the wheel slip for the wheel on the rolls allowing enough torque to be sent to the wheel with traction to at least allow it to move off the rolls.

Vehicles with "active" (electronically controlled clutch pack) transfer cases don't rely on the brakes to send torque to the front wheels.. however typically the brakes will assist with side to side braking on the same axle for improved tractive effort, whether it be a front or rear axle. If you put a CTS4 or SRX4 on those rollers as seen in the video it would walk itself off without ANY wheel slip. I like to tune the AWD systems such that they don't have to rely on brake traction intervention at all. This minimizes the invasiveness of brake activations to the driver and conveys smoothness. Of course it is nice to have the brakes there as a fall-back for side to side traction (mainly front wheels if you have a limited slip rear axle) and have them intervene during stability events if the vehicle begins to exceed the tires lateral traction capability and yaw or slide sideways. I'm not intimately familiar with the SRX4's RDM and controls but in talking with co-workers familiar with that system it is extremely capable and very well tuned (calibrated).

Front wheel drive versus rear wheel drive based vehicles with AWD will exhibit different behavior on snow and ice. In a perfect world they would be the same, but the fact of the matter is rear wheel drive based vehicles will have more of a tendency to oversteer, while front wheel drive based vehicles will have more of a tendency to understeer. For most customers who are, let's face it, not good drivers in snow and ice, we like to tune AWD systems to induce a neutral or understeer condition so vehicle handling is predictable and allows them to slow down without getting into problems.

As to what system is best for a customer...it really comes down to personal preference, how you drive, and what your expectations are. Are you willing to tolerate a lot of brake intervention? Typically when brake-based traction controls intervene they will pull throttle to keep the brakes from overheating. Personally I don't like the brakes to intervene unless I'm very near the vehicle's limit and need them as a safety net. European vehicles typically are much more conservative with their brake traction controls so with an open center differential AWD system you're very definitely going to feel them applying quite often in low mu conditions. I'll give you an example of how conservative they are. If I take a Mercedes, like the GLK, on a hard-packed snow field and start out in a straight line at wide open and gradually work the steering wheel back and forth faster and faster, the vehicle will literally come to a stop, even with it floored. Why? Because their stability controls are calibrated to virtually eliminate ANY chance of slipping. Is it a bad thing? Again, that depends on your perspective and driving style. Will everyone notice them or care? No.. and in fact some people may see that as a plus.

Since you have owned a CTS4 with electronic controls and you are more educated about vehicles than most, you'll be more adept at noticing these innuendoes and shortcomings in open differential type AWD systems.

Hope this helps. My recommendation would be.. if AWD performance is critical to your purchasing decision, wait until winter to test-drive all of the vehicles you're considering before buying.
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Well.. I suspect I don't need to wait until winter. I think I'm already sold on GM's AWD systems, as offered on current Cadillacs.

:cheers:

RAB.

TheCaptain
08-18-11, 09:38 PM
Hey RAB. I am going to add one thing in.

It's not just my SRX, every AWD SRX the dealer i purchased from has had this... 'issue'. If left to cold soak in -22*C or colder temperatures for more then two-ish hours, the rear axle will almost always disable itself until it has "warmed up". I have had this happen numerous times on mine, and other SRX owners i keep in contact with. The dealer has no fix at this time, other then to not let the rear end get cold (yea, real easy right...) so mine does sit in a heated garage, but i have gone to friends places, or to the city or something and let it sit in cold temps for a few hours to come back and have 'service rear axle' and 'rear axle disabled' come up on the DIC. This now has reduced your nice AWD (with eLSD rear end mind you) effectively down to a front wheel drive vehicle (with an open front differential). I nor other owners are not happy with this at all, as we all paid a great amount of money to have a sweet Cadillac with AWD and eLSD.

I can duplicate this condition every time it gets cold out, and i leave the vehicle to cold soak outside. All i have to do is drive for more then half an hour (or more, sometimes) and then shut off, and restart the vehicle (after a short period of being off) and the rear axle is 'warmed' up enough to be active again. Still not cool. So yes, as much as Caddy touts the SRX with an awesome AWD system (and i will too, as long as you keep it warm/moving) it has also been a pain in the butt over the winter. I really hope the dealer comes up with something this winter or i will be giving GM a call. :mad:

So, just keep in mind, the CTS uses a sweet rear drive/transfer case AWD system, and the SRX uses a fwd/ptu AWD system, that has a current flaw in cold soak temp operations. Just a heads up.

RAB
08-18-11, 10:12 PM
Hey Captain, well that's interesting stuff! Thank you for the heads up on this.
So.. the eLSD rear end on the 2nd gen SRX doesn't like to get cold. I wonder if they've addressed this issue on the 2012 model?

It's ironic you've mentioned the CTS's sweet rear drive/transfer case AWD system.. as I am contemplating right now selling my VERY NICE fully equipped '09 CTS DI FE2 RWD Sedan (18K kms on the odo) and purchasing a fully equipped 'used' 2011 CTS Premium AWD Sedan with only 1,800 kilometres on the odometer! I will need AWD this winter as I am re-entering the workforce as of Sept. 1st and will be commuting to & from work once again. I'm okay with either a (late model/new) CTS4 or SRX4, but the CTS4 I have a line on right now may just be too good to pass up. The ext/int color combo is perfect for me (Radiant Silver/Ebony), and it even has the optional 19" All-Season Tire Package, which puts paddle shift controls on the steering wheel. Decisions, decisions. :)

Razorecko
08-18-11, 10:50 PM
Hey RAB. I am going to add one thing in.

It's not just my SRX, every AWD SRX the dealer i purchased from has had this... 'issue'. If left to cold soak in -22*C or colder temperatures for more then two-ish hours, the rear axle will almost always disable itself until it has "warmed up". I have had this happen numerous times on mine, and other SRX owners i keep in contact with. The dealer has no fix at this time, other then to not let the rear end get cold (yea, real easy right...) so mine does sit in a heated garage, but i have gone to friends places, or to the city or something and let it sit in cold temps for a few hours to come back and have 'service rear axle' and 'rear axle disabled' come up on the DIC. This now has reduced your nice AWD (with eLSD rear end mind you) effectively down to a front wheel drive vehicle (with an open front differential). I nor other owners are not happy with this at all, as we all paid a great amount of money to have a sweet Cadillac with AWD and eLSD.

I can duplicate this condition every time it gets cold out, and i leave the vehicle to cold soak outside. All i have to do is drive for more then half an hour (or more, sometimes) and then shut off, and restart the vehicle (after a short period of being off) and the rear axle is 'warmed' up enough to be active again. Still not cool. So yes, as much as Caddy touts the SRX with an awesome AWD system (and i will too, as long as you keep it warm/moving) it has also been a pain in the butt over the winter. I really hope the dealer comes up with something this winter or i will be giving GM a call. :mad:

So, just keep in mind, the CTS uses a sweet rear drive/transfer case AWD system, and the SRX uses a fwd/ptu AWD system, that has a current flaw in cold soak temp operations. Just a heads up.

I have never had this issue. Although after 500 miles of ownership I like to replace all the fluids. The dealer replaced all the fluids including the rear axle with "BG" synthetic fluid. I'm sure that using a good synthetic fluid like that will make a huge difference as it wont need to warm up as long to have a proper viscosity.