anthq

Hi all

I am considering trading in my car for a C43 sedan. In love with the car, from the beautiful interior to how fun to drive it is, and counting down the days until I can realistically make the switch. We recently just got hit with a ton of snow, and after being used to RWD for so long, drove my fiance's Sentra (actually has same Contis as the C43 comes with) and was amazed at how great (relatively) the FWD was in the snow.

It got me thinking - how will the C43 fare in the snow (say with stock 18" all seasons), being AWD but with a torque split is 31/69?? This must be better than an RWD, since some power is going to the front, but does this fixed rear bias make it worse or better than a FWD car in the snow?

Asking as I am considering waiting for the S4 to come out which I believe does not have a fixed torque split and is able to shift power around to be more FWD or RWD biased.

Would I be right in ranking:

Best
1)Regular AWD/Regular 4MATIC
2)AMG 4MATIC w/ fixed torque split
3)FWD
4)RWD
Worst

Appreciate any thoughts to help me make my decision. Thanks!

Shadwell

First consideration no matter what you end up in is to ditch the all seasons (or no seasons) and use winter specific tyres.. and HiPo summer tyres in the summer...


Re the torque splitting, unless you plan extensive performance snow and ice driving you'd likely not realise a difference between the first two.. the vehicle stability control will be meddling at some level with throttle and braking in addition to the power distribution to axles etc..


And if you plan to go beyond that usage you ought be in a rally car... also a great idea

z28lt1

In regards to your question, the AMG 4Matic has a different torque split than the regular 4matic in most MB cars including the other W205s (the new E-class has something different), and most are fixed. That said, I believe there is a break-away clutch in the center diff, so it will still move some of the power in extreme traction situations to the other axle. It's just not like the fancy new electronically controlled variable systems, or even a more variable viscous system. It should get the job done in many situations.

Lots of the new AWD systems (including 4matic) make heave use of the brakes to replace what a differential used to do as well. Even my AWD big Crossover does this. These systems are effective, but will not outperform the best mechanical systems, and of course doesn't replace a true locking differential. In short, they work, just not perfectly.

To add to Shadewell, and what is often repeated in threads like this, realize there are 3 main things you need to do when you drive.

1 - Brake
2 - Turn
3 - Go

AWD/4WD only helps you with #3, and will help you not get stuck as much. More accidents occur during #1 or #2. Tires help with all 3, and are the most important if you really do plan lots of snow driving. Ground Clearance also helps with #3.

sean1.8t

Coming from old Audis with the industry leading Quattro, I was worried about how the latest 4Matic would perform. Safe to say I'm not disappointed at all. This thing is a beast in the snow and actually really fun with the rear bias. Snow tires are key though.

Bueller178

It's.....all......about.....quality......snow..... ..tires.

anthq

Definitely hear you all that tires are key (I run a set of scorpion winters myself). But, even with snows, RWD is still, to me, a ways off from the "point and shoot" of an all-season FWD (at least the getting up and going part).

As z28lt1 mentioned - brake, turn, and go - tires help with all, but coming from RWD to AWD I'm interested in how much that will improve the "go" part - in terms of not getting stuck, or driving down a straight road without the back feeling like its stepping out. Correct me if I am wrong, but it sounds to me that despite the rear bias, the C43 4matic would still be better in that respect than a similarly equipped RWD or FWD. Due to traction/stability control and/or it not quite being really "fixed".

Bueller178

AWD of any type > FWD or RWD.


In the go department it makes a huge difference over RWD/AWD.

anthq

In so many words - this is what I wanted to confirm. Thank you!

Standingoten

Came from 2007 Infiniti G35x and a 2014 Q50S Hybrid AWD.
The 4Matic on my C450 is better than the Infiniti system in my initial drive in snow.

With the Infiniti system, the rear end likes to stick out and the car likes to go sideways before the front wheels kick in. The C450 is more controlled and keeps the car pointed straight.

MASSC450

I've owned a 2015 C300 Sport 4Matic, and I currently own a 2016 C450...both vehicles do very well in light snow conditions with just the stock 18" AMG wheels/all-season run-flat tires. In both cars I've driven in up to 6" of snow with no major issues.

Will dedicated snow tires perform even better, sure they will, but if it doesn't usually snow a lot in your area, no reason not to use those stock all-season tires.

sean1.8t

Full time mechanical AWD vs part time electronically controlled AWD.

Mechanical will always win this matchup.

I've experience AWD in a 2008-ish G35x. It was pure garbage if you ask me.

anthq

This is the exact behavior I was afraid of - that because of rear bias, it behaving more like RWD. Like I said - even with snows, my Camaro driving a constant speed down a straight, snowy road, I can sometimes still feel the back wanting to kick out. I am glad to hear that it sounds like AMG 4MATIC system does not behave like this and can handle snow better than an otherwise FWD or RWD.

z28lt1

My G35x was fine in the snow. As you noted, it is electronically controlled, but it is still controlling a mechanical clutch. Snow Mode changes it to a 50/50 split at low speeds (the time when you will most need AWD in bad weather). Have not yet had a chance to compare it to the C450, which may indeed be better, but I wouldn't call the Inifiniti garbage.


If you are driving straight, at a constant speed and the back end is coming loose, the drive wheels aren't the issue (unless you are one of those drivers who can't keep a constant pressure on the throttle and are constantly lifting and pressing on the throttle to keep a steady speed. I'm going with that's not you....)

Bueller178

Just came back from a drive in a snowstorm. As usual, car did very well. I like the rear biased nature of the AWD, it steps out if you punch it but driving "normal" it's very neutral.


This car is a lot of fun.

anthq

Ha-ha - no...

Maybe I do mean slight acceleration. Rather than traveling at a perfectly constant speed, I mostly meant not necessarily sudden punch of the throttle or acceleration. Such as after getting up and going, gently going from 5->10mph and feeling the back not being planted - unsettling, especially when there are cars street parked...

But could there not be a situation where the torque required to maintain 10mph would cause the rear end to break loose in snow? Not necessarily perfectly flat ground, or same snow depth/packed-ness, etc...

z28lt1

Of course accelerating or going up a hill will change things, and you are asking the tires to do more. Steady state cruising does require some torque, but if the backend breaks loose because of too much torque to a wheel at steady-state cursing, you were right absolutely right on the edge, and going too fast for the situation, and in most cases, like that, having additional drive wheels wouldn't help much.

Note here, we are talking about drive wheels causing a traction loss, which is different than skidding due to other traction loss reasons. If the roads are slippery, and a change in traction (like a slick spot or something), combined with say a slight turn, or even the crown of the road, the back end may come lose, which isn't the example I was talking about above. Although, generally the drive wheels don't matter in that case either. At least, the drive wheels won't prevent that, but may make it a much easier recovery if you are still on the throttle.

In your Camaro, it is obviously a high-torque vehicle, making it harder to manage the throttle, and while they are much closer to 50/50 weight distribution than ever before, they still have more weight on the front end. The problems are compounded because when the car starts to slide, the first reaction is generally to lift off the throttle and brake. Which might help in a front end slide, but it the wrong thing to do in a rear and slide since you are shifting weight off the back of the car. It is also that reaction that takes away the advantage of AWD, since for most people who have not practiced sliding around, the natural instinct is off the throttle.


Cars are good at going straight, even in bad weather. The whole object in motion stays in motion thing we learned in school (although in this case we have friction ruining its motion, and why we still need some throttle at steady state) It's accelerating, stopping, or turning (even a little) that causes problems.

Either way, I think you have your answer, that the MB 4Matic is a pretty good solution, and certainly will be better than the Camaro, all else equal.

sean1.8t

My brother has been a Nissan master tech (GTR certified) for over 15 years; even he disapproves of the infinity's "AWD" when comparing to the likes of Subaru/Audi.

And like Ike I said, the Benz is amazing. My Blizzaks are so good that the back end doesn't ever want to step out unless you really goose it to break them free. Which I can't not whenever is appropriate

anthq

Z - I appreciate your thouhtful reply. All makes sense &I is clearer.
I think the distinction I'm trying to get at is in RWD rear will step out if too much torque is applied, with FWD that dynamic doesn't exist you just sort of sit there or make slower forward progress. In a car with AWD that can shift all power to the front, I expect it would just act like a FWD. With the C43, it sounds like it will act that way UNLESS you really get on it and force the rear wheels to step out.

Bueller178

This is not accurate. If you give enough power to a FWD car it will step out. If you are turning it will understeer more than if not under power.


You are getting the same physics, they just affect the car in slightly different ways.

sean1.8t

It's honestly been over 10 years since I've owned, and thus, driven a FWD car in the snow, but I find it hard to imagine the back end ever stepping out unless you're pulling the E-brake...

I remember FWD cars having a very good dynamic for turning in the snow. The front pulls the car through the turn and the rear is there to follow suit and maintain a good balance for the rest of the car. But idk, it has been over a decade like I mentioned.

sean1.8t

OP PM'd me some questions and after typing out a long winded answer, I figured it wouldn't be terrible info for this thread:

anthq

Thanks again to all for your input!

Xtrema

On C450, tail end will want to swing if your tire isn't sticky.

I think I screw up on C450 by picking Winterzotto 3 instead of old trusty WS80/LM80. My old S4 with Sport Diff was a tank in winter with LM60s. I definitely can easily get my tail out with C450 with Winterzotto 3.

That said Winterzotto 3 is definitely more fun on dry pavement. Ice/snow, Blizzak LM were better.

I have WS80 on a old Jetta VR6 project car, FWD with WS80 in -20C with snow/ice is pretty good too.

J.M.G.

In my option, it really depends what you want to do. For most comfort during a nice road trip, standard 4matic is the way to go. This awd goes down the Autobahn like a rocket. Totally stable. Snow? Ice? It just goes. However, this stability is also the downside of that system - when you want to do some spirited driving including turns, the AMG 4matic is way, way more aggressiv. Less understeer! So I would say:

1. 4matic
2. AMG 4matic
3. FWD
4. RWD

all with good winter tires with at least half thread left!

tpmbz67

I've seen it recommended that the car be set to "ECO" mode for snow driving. Is this the right idea? Also, where I would absolutely buy winter tires if I lived in an area that got frequent winter snow, as an occasional weekend snow driver I went with the Michelin Pilot AS-3. Having driven them for a week now in dry conditions I can say there is a distinct difference in ride quality to the Continental run-flat summers that came stock and any idea I had of swapping them out for the seasons is long gone.