flj

I picked up a GLC 300 back in July (picked up as opposed to custom order ). Not happy. For one, it seems really really noisy and, worse, I'm not thrilled with handling, The car looses grip for nothing, To this end I've developed tire-pressure OCD, I'd don't know if it is the tires or the suspension, or both, but I'm beginning to think the air suspension is a minimum requirement, at which point you may as well get at least the the '43 model (which is this the trade off I made, they had a loaded base model on the lot and the price was a lot better than a custom order ) . Sad to say, but I had no idea I'd feel unsafe in a merc. Has anybody else experienced handling issues (slip, fishtail), can this be fixed with some better tires? I'm about ready to trade it and let somebody else sort this out.

fabbrisd1

1) 18" or 19" ?

2) Tire Pressure OCD - at what pressure are you running ?

3) What "profile" are you normally set to at highway speed ?

4) Personally - for my driving I am not a fan - but not a enemy of "Extended Mobility" - that way they "feel" to me is the way they are designed - very/very stiff sidewalls that will maintain tire integrity if you lose air - on turns/maneuver at speed - all is well for the 1st seconds - then thre tires rolls to that stiff sidewall section. I personally choose to by a "normal tire set" at 1st opportunity and keep the OE Extended mobilty set in my garage when down-the-road I will eventually sell/trade it off. I have MB's that have hi-perf tires that are $600 each - so $600-$700 for four set doesn't really hit me hard..

flj

Currently running on 33 PSI cold inflation pressure (and the idea is to keep increasing 1 PSI per week to see if there's any noticeable difference)

For the most part I just let it default to "Custom" . Mostly because there are other people on the road
I think of S as "great for merging" and "E" for longer trips on cruise control. Had there been an option to set it, I'd probably have set "S" as the default as I do like the improved throttle response
Funny thing is though, whenever I've experienced slip, the speed has been below 40 miles per hour

Yeah, set of decent tires is well worth it, I've been thinking about some Michelins,


All this being said, I'm also wondering if this is could be a quirk of the electronic stability assist (one of these days they will have to come up with a sexy name for that ) .

DDGator

Under what kind of conditions are you experiencing this slipping and fishtailing? It is to the degree you actually lose safe control over the vehicle, despite the electronic nanny systems?

PickyBoy

No it's not you... and the tire won't change anything. I have the Michelin X-Ice as Winter tires. Last week I explain the difference between mode... For the traction part I told her that E and C are the mode that you have less traction; you can/will loose control of the back of the car on tight turns at slow to moderate speed (don't want to test it too much). In S (didn't test S+) mode you have more traction at all speed. If you are in E or C and you have a tight, slow speed turn, you will have the press on the gas more then you would normally do and the car will be stable. After that I did a demo

But we were thinking that Mercedes should have gave us the best traction in E mode, normal at C, Good at S and let the car slide at S+... but who knows maybe there's a logic behind that

Condition: cold Canadian Winter. During summer I don't really care because I know that I can keep/regain control of the car/SUV Coupe.

gholland

My 2018 GLC300 18" handles better than the Infiniti FX35 I had for a few years. I drive 80 miles a day in all conditions (Colorado/Denver metro area), this is my 2nd winter and I have nothing but good experiences with the car as far as handling goes. I almost never drive in 'C' mode and haven't driven more than 100 yards in 'E' mode. I usually drive S++ unless it's just a very short trip. On snow/ice I drive the S++ mode and down shift manually a lot to slow down. I haven't fishtailed unless I want to around a corner to mess around when no one's around... but... haven't seen it otherwise.

gh

flj

That's helpful and confirms what I suspected. Actually, I'm pretty sure I've been in "C" mode when this happened and when I've tried to provoke it, whiteout success, I've been in "S" mode.

karmikan

A bit confused by this thread. I have the standard suspension and I've never been able to provoke any instability in my GLC other than on a very icy surface. Even then, the ESP quickly came to the rescue. Coming from a BMW 5 series sedan, the high center of gravity of the GLC took some getting used to in fast corners but I've never experienced anything remotely similar to your description. Do you have RWD or AWD? Is your ESP warning light on?
BTW - the "C" in Dynamic Select is "Comfort" not "Custom". You can customize the dynamic settings through the "I" (individual) sub-menu

flj

Standard suspension, RWD. I have to admit I have been VERY surprised when this happens. Very, and last time it was downright spooky, I lost grip as if I was cornering too fast on a gravel road, I just slid sideways, Not sure about the exact speed but somewhere in the neighborhood of 35. I've been going down that road for over 10 years without having experienced anything like it. There's another place where I've had rear end slip twice, at first I thought maybe this is a road surface issue but I've not been able to provoke it, and it's not for lack of trying. Which is what led me to obsess over tire pressure. Have not seen the ESP lamp come on. However, the ride quality seems to have deteriorated. Really, I'm not sure what to make of this. For all I know there's some electronic bit somewhere that needs fixing as I'm all seeing lag in the e-brake application.
I haven't taken this to the dealer yet. they already have a voodoo doll of me, so what's one more pin.

All this being said, I can't help but wonder if the real thing you want is what is on the AMG 43, air suspension and wider rear tires .

On a side note, I'm not familiar with the BMWs but I do love me an E class,

6G Schnell

flj

19"

karmikan

That explains a lot. I have an AWD so my experience will be different to yours. My 5 series was RWD and I had to be a bit more careful on "iffy" surfaces (gas tank topped up, slight delay accelerating out of a corner etc.). That said, the ESP always calmed things down. The higher center of gravity of your GLC will amplify the normal RWD tendency to fishtail. However, you seem to have an extreme case. It's possible that there's a problem with your ESP.. A couple of tests you might want to consider - if you disable your ESP does the warning light come on? It should. To check that the system is operating, drive down a section of road where you have noticed some instability, turn the ESP off and drive the same section again BUT PLEASE BE CAREFUL. The handling should deteriorate, if it stays the same, it's possible your ESP system is faulty and needs to be tested/re-programmed.
As far as I know, air suspension improves the ride but does little, if anything to improve the handling. How much of a delay do you get on your e-brake? Mine takes maybe 1/2 sec to 1 sec from stopping the engine to the brake light coming on.

flj

That's a good idea, I will try that .

As for the e-brake, usually it is near instant. Keep foot on brake, open door and you can hear it engaging immediately. Then, occasionally, there's a considerable lag, lets call it 2 - 3 seconds.

6G Schnell

flj

My understanding is that the label on the B pillar is for informational purposes (max cold inflation pressure) and that the label on the fuel door is for operational information, ie what is the cold inflation pressure that yield the best combination of safety and comfort. I understand that there are a lot of compromises in those numbers but I have neither the time or nor the inclination to take the car to a track and work on an understanding on whether or not I agree with the compromises they made; I'm quite prepared to take the manufacturer's word for it; they say 32, then that works for me unless of course, I think 32 is just too much compromise and not enough "bite". I've been doing 33 this week and Saturday I'm going to 35. We shall see

redrover22

It's all in the tyres. I was shocked like you but switched to good quality non runflats and am now very happy.

RedKloud

The suspension has been tuned for highway cruising. It is certainly not a canyon carver - too much body roll. It also seems to get upset by certain bumps at lower speeds.

Jetfuture

Definitely get rid of the run-flats as soon as possible. Big change when you go to a standard tire.

fabbrisd1

"Slip" and "Fishtail" are extreme comments for a GLC - both infer loss of traction at speed - and certainly all "not good"...

On the chance you drove a sport sedan before changing to a GLC/SUV luxury sport SUV - the higher center-of-gravity of the SUV does "change" the driving characteristics at compared to a sedan - also since the GLC has a relatively "quiet" cabin as compared to most compact sport sedans - MANY of my customers find themselves driving at higher speeds in their GLC more easily than many compact sport sedans they drove before.

In your GLC - what "profile" you choose for your GLC changes the characteristics for your GLC - in comfort with "widest" steering ration as compared to the increasingly "tighter" more responsive steering ratio moving up thru Sport and then to Sport Plus.

For me - I am "normally" in Sport steering profile which I have adopted in my Indiv profile setting for my "drive style" in Comfort I at times tend to "over react" with the "looser" steering response - for me.

I personally consider the GLC - both RWD or AWD - the best "driver" in this segment - yes I am a MB guy - but overwhelmingly my impression is reinforced every day by my GLC customers..

flj

I'd agree about the "slip" and "fishtail" but I don't have any other words for it. "Whole car sliding" and "rear end sliding" maybe, thankfully no plowing I can't tell you the exact speed, but I've been going down these roads for years I'd say 35 MPH or less, the posted limit is 30 and 35 respectively. I'm pretty sure I was in comfort, C. Though, after that last 'whole car slip' I've pretty much switched to sport, S in the hope of getting better bite. I've also upped the cold-inflation pressure to 33 PSI, with weekly checks. That last slip was a serious WTF moment though. First time the rear-end slip happened, I was merely considering it a tire pressure issue. The next time it happened I _knew_ it wasn't a tire pressure because as I'm more on top of tire pressure than ever before. I've upgraded my tire pressure gage and re-calibrated sensor system. I see faster pressure loss on the right side. Maybe the bead needs re-seating, IDK. The rear end slip happens in the same spot except for when I try to provoke it. Maybe I should turn off the ESP and try.

ItalianJoe1

I can't imagine there is something that seriously wrong with the handling if everything is working as designed.

How is the alignment? I've seen them off spec pretty bad even when new, and in poor traction conditions it can amplify the feeling of instability. My '18 GLC drives awesome but I don't have cold weather here and it's got only a couple hundred miles on it so far, but I drive them all the time and never noticed bad handling, even with my quite aggressive driving style.

flj

So, I'd just like to thank everybody for their input. I think I've built and understanding of what's been going on here. Partly the temps have been dropping and for that reason alone, one have put a little more effort into tire pressure, and partly (and why I haven't noticed that before is beyond me) on the road where the rear end skid happens ( I called it fish tail i the original post) there are a couple of fairly large traffic circles and on the entry/exit there are concrete pedestrian crossings. So you accelerate on the black top and suddenly there's slick concrete surface, wheel slips.

The other thing is tire pressure, after some experimenting, I re-discovered what I already knew. cold-inflation pressure = pressure when tire temperature match ambient temperature, add 2 psi for winterish temps and 1 psi for every 10F diff between garage temp and outdoor temp, (outside 30F, garage 50 = add 2 psi ). Getting more air in the tires made a huge difference.

In the process I also came across the "companion app", which is a handy-dandy companion to you MB fleet, fuel state, air pressure and more, if you haven't already, go download it to your phone.