While performing on-line due diligence on the GL320 CDI I was convinced the 2008 model had this feature as standard equipment. Searching this site provides numerous posts alluding to this feature.

However, when we test drove the Mercedes (which we liked immediately) the dealer rep stated that while the GL has standard Airmatic suspension it does not provide automatic load leveling.

Any information that will remove confusion and definitively answer this question will be much appreciated.

 

Well, if you see how the back rockets up and then back down (when you close a door) when you unhook your trailer, I think you would be convinced of this feature as a component of Airmatic....

 

It is definitely a feature of the airmatic suspension.

 

Follow the sticky link at the top to the online GL manual and see what it says.

 

I had a quick look this morning, and there does not seem to be a direct entry. the only thing I saw is what I mentioned, don't get crushed under the truck after you unhook a trailer....

 

I will confess that I did not look myself . But it is weird that nothing is mentioned. I will pull out my paper manual later today and see if that has anything.

 

I did say "quick" look. Dude can dig it up himself. I'm too busy reading Steve's eating magazine...

 

I'm not sure about US models, as your packages are different, but on Canadian GLs, the Airmatic is indeed self-leveling.

The Active Dampening System is standard on the 550, optional on the 450, and not available on the 320 up here.

 

Last night as the rain came through and air cooled off, I thought I'd cool the inside of the garage a bit (insulated doors) while I had the chance. Without turning the GL on, I opened the rear hatch and the wife and I sat in the back. About three minutes later (it seemed, anyway), my feet lifted off the ground.

I think active dampening is different than airmatic and load leveling, BTW. I think. And as for reading the food magazine - PM me your address and I'll send you Volume 1, Issue 1 once it's printed.

STP

 

What's this "food magazine" of which you speak?

 

Thanks for all the replies. I convinced the dealer to let me borrow a GL320 CDI for the day so I can convince myself of the auto leveling suspension as it relates to towing. As many have pointed out while Mercedes alludes to a self leveling function in the suspension in the GL I have yet to find an explicit reference to it other than on their website. I remain convinced that the GL will self level within its adjustment capabilities (+/- ~2").

When the GL gets here I will hook up my trailer (empty @ ~2000lbs and loaded with a 993TT @ ~5300lbs total) and take it on a loop of the city. Our crappy NEO roads should provide an acid test of the GL's towing capabilities. I will update the thread when I complete the loop.

StevethePilot- you are correct; active damping is different from the Airmatic suspension but I am not certain if it uses the air suspension to perform it's damping function or uses a magneto-rheological fluid as in the GM/Chevy system to alter the dampers compliance. My gut says that pneumatic systems won't respond rapidly enough for active damping so it must be independent of, and therefore in addition to, the Airmatic.

 

www.EatFreshAZ.com

(Man, how much free publicity can I get?! LOVE IT!)

STP

 

In a previous post I was going to connect our trailer to the GL320 CDI to help us establish the towing capabilities of the vehicle. We accomplished only half of our intended goal. Because the GL delivered to us did not have a brake controller installed we only towed our trailer empty (~2000 lbs). We hooked up the trailer and went on a ~30 mile loop of the city. With an empty unbraked trailer I can say the GL performed in a satisfactory manner. The low end grunt of the diesel was particularly evident at traffic lights. If I lifted my foot off the brake pedal the GL would roll forward at idle even on uphill grades. For comparison our Tahoe would not/could not do that and would be anchored in place by the weight of the trailer until I depressed the accelerator.

The Tahoe accelerated to highway speeds more briskly than the GL but once we got to highway speed (65-70 mph) my wife and I both agreed that the GL appeared more effortless on the highway. The GL pulled straight, did not wander, and maintained its speed on uphill grades (with and without cruise control) better than the Tahoe. Lastly the brakes of the GL are significantly better than the Tahoe. It helps having 14.7" discs in the front. In some respects the brakes had better pedal feel than our '06 M5.

As others have commented the side view mirrors are really not adequate for towing. Telescoping mirrors would be a nice option on the GL but nothing is perfect. While the 7-speed transmission of the GL is remarkably smooth it would be nice to have the current gear displayed rather than having to resort to pressing the +/- shifter buttons on the steering wheel (if there is another way to accomplish this please advise). IMO the GL seemed to want to run in 1 gear too tall from what I felt was optimal (6th instead of 5th, 7th instead of 6th in particular). Based on my limited time with the GL, and no operator's manual in the glove box, I could not find a simple way to switch between manual and automatic gear selection other than the transmission stalk on the steering column. It appears to be either all manual or all automatic with the GL's transmission. On the 7 speed SMG in the M5 if you are in manual gear selection and come to a complete stop in any gear, 1st gear is selected automatically but the tranny remains in manual mode. I am certainly splitting hairs here since the GL tranny is exceptional in all other respects but I think the "user interface" could be improved.

As far as automatic load leveling is concerned it was not immediately apparent that the GL's Airmatic suspension was adjusting to the trailer pulling down on it's rear end. However the trailer started out very level to begin with so perhaps there was no need for the Airmatic to adjust to the load. I should mention that the GL we drove did not have the Adaptive Damping System (ADS) as an option and I am becoming more convinced that this is required for the type of load leveling that I am accustomed to in our Tahoe. Regardless of auto leveling or not the GL performed adequately under the conditions of our test.

Bottom-line we did not accomplish what we set out to do as far as pulling a fully ladened trailer but the GL gave every indication it was up to the task.

Now the ball is in the dealers court to present us with competitive pricing on the GL. The vehicle we drove has an MSRP of $68.2K including destination & delivery charges. I anticipate paying a lot less than that. Any thoughts on where '08 GL320 CDI sell pricing is?

Thanks again for all the input.

 

I think you are a little confused. Your Tahoe rode on springs, and had helper bags to prop or lower the rear to achive leveling. The GL has no springs at all, and rides on air bags on all four corners. The leveling effect is a natural component of this, as the car has to have some reference to figure out how much air to pump into each corner, and that reference is level. So, get out of the front seat, and a big blast of air comes from the truck and it lowers at the front. Throw a bunch of junk in the back of the car and turn it on, then the back pops back up to level.

If you spend any time at all with a GL at all, you will get to know it's habits of constantly leveling, and re-leveling itself, even when it is just sitting there.

As for ADS, that will only impact the stiffness in day-to-day driving. As far as I know it only intervenes in leveling, in that it will say put more air into the front left corner of the truck in a fast right hand sweeper to give the perception of "flat" turning, and does this in a very active way. But this has everything to do with side-to-side leveling and body roll mitigation, but nothing to do with load leveling.

I tow a trailer with my GL, and I can tell you it very obviously auto levels front to rear. I think the reason you don't see it doing what you expect, is that it levels at all four wheels, unlike your Tahoe that would just move up and down at the rear...

 

ADSII will not dynamically adjust the ride. It has three modes. Normal is a standard suspension ride. S is a firmer ride and C is a very soft bouncy ride. ADS regulates the air in the suspension based on your selections but does not adjust individual corners to give the impression of "flat" turning.

ABC (Active Body Control or something like that) is a system on the some S class cars that will constantly adjust the car to provide a "flat" ride experience by dynamic adjustment of each corner.

The only US model in '08 with ADSII was the GL550. All models will have ADSII available in '09 as an option. In my view an absolute necessary option.

 

Well, you own(d) one so you should know, I was just repeating what our salesman told us, whan we test-drove the 550.

Regardless, there is no effect on load leveling...

 

Brocktoon- thanks for the reply; I think your description is consistent with what we experienced during the brief time we had the GL with the empty trailer attached. I appreciate the differentiation of the ADS (apparently identical in function to the EDC, electronic damper control, in our M5) from the Airmatic function as well as your description of the fundamental differences between the Tahoe air suspension and the Airmatic independent 4-wheel suspension.

Salespeople do have a way of confabulating the function of these systems into half truths if their desire is to tell you what they think you want to hear. It is the rare dealer rep that will tell you they don't know and actually do some research to find the answer to a question of this nature.

 

I followed your advice and read the sections I could find that pertained to these subjects. Unfortunately that's in part where I got the idea that the ADS might be involved with the load leveling. Without quoting the manual, in the sections relating to towing a sequence of steps is included for setting presets for the suspension, Airmatic and ADS, prior to connecting a trailer. Since the vehicle I drove did not have the ADS as an option, and we never notice an overt leveling of the suspension with the trailer attached, I inferred incorrectly that the ADS might have a roll in the leveling function.

Thanks to the members of this forum my confusion has been vanquished and I have learned a good deal about the GL in the process

 

Hope you get one. I don't think you'll regret it.

 

I'm curious why you say this. Of course, 07-08 320's didn't offer this as a option, but wouldn't you end up leaving it in one mode most of the time, anyway?

 

I had Volvo with the ride control "active chassis" foolishness, and when the salesman was explaining it to me I asked him if he could just solder the switch into 'comfort' mode.

I guess for some folks, it means something; for me it's just a gimmicky bit of pseudo-race-car crap like the paddle shifters.

 

When you are driving a 5400# truck at 80 MPH on the interstate in Colorado the S mode is a welcome addition... it tracks like a sports car (well pretty close.) It is a good firm ride and really keeps the GL from leaning. On the normal roads I used mostly the standard setting and occasionally the C mode on really washboard roads. I found myself adjusting the ride quite often.

If as Kaumajet posts above you think it is a "gimmicky bit of race car crap" then don't buy the option. I would recommend you drive a GL with the option and then decide for yourself, if for nothing else additional safety. Once you drive the GL on curving roads you will decide to get the option. YMMV

 

Thanks for the explanation - that makes sense. I'd be curious to test this feature out - but for the meantime I guess I'll have to live in blissful ignorance.

 

Just to add to the confusion, I just picked this up of the MB intl' site. Looks like roll mitigation is a component of ADSII.

AIRMATIC DC
The semi-active AIRMATIC DC (Dual Control) air suspension irons out bumps in the road. The electronics provide four different damping stages (Adaptive Damping System ADS II), which automatically adjust the damping force at each wheel to the requirements and road conditions at any given moment.

On poor surfaces the body can be raised manually by approx. 25 mm. It is automatically adjusted back to its normal level after a speed of approx. 80 km/h is maintained over a long period or where a speed of approx. 120 km/h is exceeded. The basic settings for the AIRMATIC DC can be selected at the touch of a button with a choice of "comfortable", "sporty-comfortable" and "sporty" modes.

Thanks to the Adaptive Damping System ADS II, body roll is automatically reduced when cornering, providing added driving pleasure. If the sensors detect a sporty driving style, the comfort-oriented basic suspension set-up is automatically adjusted to become more rigid. The system also features all-round self-levelling suspension, which also provides virtually constant ground clearance even when the car is fully laden and, in turn, more stability and dynamism. At high speeds the body is automatically lowered in order to reduce wind resistance.

 

That sounds pretty nice...:-) I don't know if Airmatic DC (Dual Control) is new or not. I had not heard that term before but it sounds like a poor mans ABC system. Based on this description I would really want the ADSII Option available for the US '09 models.