My vacation home has a steep gravel circular drive that goes down steeply to the house and then back up steeply to the parking lot. Going up the rear wheel on the inside radius slips and digs up the gravel, leaving deep ruts. My son's Subaru Outlander does not slip at all.

I have turned off the ESP and that helps a little, but still not as good as other vehicles I have owned.

Any suggestions?

 

You have a lot more power than the Subaru, especially at at 0 mph.

Try the off-road mode, which gives more gentle application of power, to not break traction. Definitely not Sport Plus.

 

I think it's weight + rear bias of the GLE.

The GLE, especially the "e" version is way heavier than the Outback, likely by 1 ton or so. Additionally, Subarus are 60:40 and 50:50 (front:rear) power distribution ratio in my understanding, while the GLE is more dynamic and rear biased by default, explaining why you see a slip of that rear wheel first. Once the slip is detected, some of the power gets reallocated to the front wheels. As mentioned above, try playing with drive modes.

 

On W166 there are gravel and snow drive modes, give those a try. I scaled very steep, rutted and rocky trailhead roads in Colorado in the W166 with no problems using regular 4MATIC.

 

Others have already hinted in the direction of the differences in AWD systems. Subaru's symmetrical AWD system has a few things going for itself when it comes to traction. For starters it uses equal length half shafts so front and rear axles are powered symmetrically. The weight is also much more balanced compared to the nose heavy Mercedes, further improving traction from a dig as the rear isn't lighter than the front. Additionally, similar to Audi's longitudinal quattro system, the Subaru system powers both axles from 0 mph. Favoring the front as said with 60% going to the front and 40% to rear adjustable in real time to 50/50. Quattro is the opposite sending 60% to the rear and 40% to the front, adjustable to up to 70% to the front and 85% to the rear w/o the help of ESP.

4Matic on the other hand at least the modern versions favors the rear axle. Essentially sending almost all the power to the rear wheels first. Then when it detects slip it starts sending some of the power to the front using a multi plate clutch in the transfer case. This will always result in a delay and the rear wheels in adverse conditions will end up slipping. Worst case this can even get you stuck if the rear wheels manage to dig themselves in before enough power is diverted to the front wheels.

There are plenty of YouTube videos you can watch of 4Matic in the snow vs quattro for example. Both 4Matic and BMW's Xdrive tend to struggle if there's little traction. The electronics scramble to send power to the wheels with traction, whereas quattro and Subaru's system don't have that issue, because all 4 wheels receive power out of the gate. 4-Matic and Xdrive focus more on driving dynamics under normal traction by making it feel close to RWD, but have the ability to send some power to the front when needed. Quattro and Subaru's system are more utilitarian.

The one exception is the G wagon, where you can manually lock all three differentials to instantly send power to all the wheels that have traction from a dig. The regular GLE on the other hand has no locking differentials whatsoever, so it tries to use the brakes to manage slip on the rear wheels as it's trying to send power forward. The AMG 63 at least has an electronic limited-slip locking differential on the rear axle allowing for actively managing traction between the rear wheels and sending the torque to the wheel that has most traction instead of spinning the one that doesn't. The open differential in the regular GLE will struggle in the same situation and as said the brakes have to be used to redirect the torque, but engaging the brakes is much slower to manage the spin of one wheel vs the ability of the clutch pack in the LSD to lock up and redirect the torque to the other wheel. This is essentially when you find out that the U in most SUVs is more marketing than reality. You need locking differentials or at least an LSD in situations like this, or at a minimum a more offroad suited AWD system like Audi quattro or Subaru's symmetrical AWD.

 

I have not found those modes. Sounds useful.

 

Did try off road. Did not seem to change the driving dynamics, just give me a lot of off road info on the dash.

 

Thanks. Have tried all modes including manual shift starting in 2nd gear. The best result was from turning off ESP.

Wish I could lock the diff.

 

As @superswiss mentions, quattro is a good system. Depending on the quattro flavor, there are many, a torsen device is positioned between front and rear axles which gives near instant torque transfer. I had a gen 2 Touareg with a torsen center coupling and it was a great system.

MB's 4ETS is excellent and nearly perfectly simulates a locking differential between a pair of wheels. 4ETS individually actuates brakes which sends torque to the opposite wheel on the same axle.

Because 4ETS is standard, any traction shortcomings on the V167 GLE are related to the fore-aft wet plate clutch variable torque coupling which replaced the traditional chain-type transfer case on W163, W164 and W166. Cayenne uses a nearly identical fore-aft wet plate clutch device, departing from the chain-type transfer case in 955/957 and 958. Why did MB and Porsche change t/case designs? Cost.

 

Page 172 of the manual. Selecting drive programs.

 

All well and good but doesn't give me a solution for the GLE.

 

Correct, it doesn't. There is no solution, other than replacing it with one that is more offroad capable w/o digging itself a hole in your gravel driveway. The AWD system is what it is. Use the right tool for the job as they say. The GLE is more at home in your local strip mall parking lot.

 

The solution is to buy another car. Toyota 4Runner or Ford F-150, for example. Or a G-Wagen.

 

As much as I like my Mercedes, I'll take the 2001 Subaru Outback I've owned since new when it snows. Most reliable car I've ever owned.

 

You are right but it is a shame that this limitation could be solved by software. The hardware is capable and in place. All that is needed is a equal power distribution software mode.

 

A few things here worth noting...

1. The OP complaint is about digging holes in gravel, which is more a driveway maintenance burden than a talk about off-road capability of the vehicle. The vehicle gets to where it needs to be, just in a different way than the Subaru.
2. Comparing a light Subaru to a heavy plugin-in GLE is just not right. It's 40% heavier, so the forces pulling the vehicle down that driveway are significantly higher.
3. While the GLE is rear-biased, it doesn't mean that it's RWD until a slip is detected. It's RWD until you need more power or a slippage is detected. You can monitor what axles are engaged on Vehicle details screen. Push that throttle a bit harder and you'll see that boxes axles are getting power applied.

 

@parato what happens if you do a test where the vehicle speed is maintained at a crawl, <5mph all the way up the driveway? Can you do this test and report back?

 

You could try reversing out of your gravel driveway to see if that makes any difference with the gravel or park up top and walk.

 

A "driveway maintenance issue" is very condescending. I have used that driveway for over 50 years and dozens of vehicles. The GLE is peforming uniquely poorly. The only one I recall that had more trouble was my father's 1979 rwd Lincoln MKV.

The subaru was mentioned as a better peforming AWD system. My rwd 2023 BMW Z4 which is lighter than both SUV's also has tire slip page... Which is why we tend to avoid using rwd vehicles.

I dont care what the bias of the awd system is or how it can be viewed. It does not perform effectively in this use case and could be fixed with a software upgrade.

 

The drive is narrow and tight radius to back safely. The whole purpose is to bring groceries and belongings to the front door.

My GLE failed where many other cars perform well.

 

I have tried without improvement. The best result has been to turn of ESP but it could be better.

 

The offroad mode is technically supposed to distribute the power better to the wheel(s) with traction, of course it's still within the mechanical limits of the system. I know it's been mentioned already, but it's worth reiterating just how heavy your vehicle is. The 450e is a fat 700 lbs heavier than the 450 (5745 lbs vs 5060 lbs). That's a lot of weight to drag up a hill. Also, it hasn't been asked yet, but what kind of tires do you have? Getting a set of all-terrain tires might give you a different outcome. At the end of the day, the tires are the only thing between the road and the car. The better they grip, the better it'll climb.

 

Oh, I apologize as I didn't mean it to sound like that at all. I was focusing on the fact that we're not talking about the inability of the vehicle to climb it but the issue of damaging the gravel driveway, which you subsequently need to fix (I.e.., more maintenance overhead for you).

 

To support @parato ’s idea of “software update”.

A drive mode could be added where the center wet multiplate clutch is closed, thereby locking front and rear propshafts. 4ETS programming will address left-right wheelspin on each axle.

My opinion about such a drive mode is these latest generation center wet clutch devices are wimpy and not up to the task described above. The duty cycle required to deliver good AWD performance is too much for the watered down t/cases used today by MB and VAG.

Another option is pave the driveway or regrade the driveway, which means significant lengthening and lots of cut/fill. Or buy a 4Runner.

 

Yeah, many overestimate AWD systems. They are great for the road in the wet and snow, but not really for offroading. I know the GLE is marketed as offroad capable and even has an offroad mode. It can make it up a hill in the dirt or gravel if it really needs to. Subarus are not to be taken lightly. They are quite capable, compared to some other AWD cars.

It's worth pointing out, that the National Park Service as of August 2024 has begun threatening drivers with $5000 fines and up to six month in prison if they are found to offroad with an AWD vehicle, instead of a proper 4WD. It was in the news recently after they sent a letter to a Subaru owner who was seen offroading, and threatened him that he'd be fined if he did it again. I guess they got tired of rescuing folks getting their AWD vehicles stuck.