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Air suspension benefits?

Air suspension benefits?

Can someone point me at good information on what the air suspension offers? Not the raising and lowering at rest, I don't care much about that. I care about if it helps while driving. It says in the blurbage it lowers to help improve wind resistance...but how much does that help? Is the ride better?

I tried Google, but the links I found mostly point to off road and performance driving stuff. I'm interested in how it'd affect daily driving.

Anyone out there knowledgeable on air suspension?

XrstalLens | 26 December 2011

Here's a brief article I found that talks a bit about why reducing airflow underneath the car is desirable. That is one of the main points, from what I understand, of the benefit of the air suspension - it can lower the car at highway speeds to reduce airflow under the car.

http://www.autozine.org/technical_school/aero/tech_aero.htm

Here's another very interesting article that basically explains that up to 35% of a car's drag comes from the underbody.

http://autospeed.com/cms/title_Modifying-UnderCar-Airflow-Part-1/A_2455/...

Having the air suspension means you can have your cake and eat it too: it can be very low on the highway where clearance is not needed but be raised to clear obstacles when needed at lower speeds.

ckessel | 26 December 2011

Seems odd they tout 5% range gain with the 10" aero wheels, but don't mention any range gain at all with the air suspension (both cost $1500).

Volker.Berlin | 27 December 2011

Here is another thread that discusses the pros and cons of air suspension:
http://www.teslamotors.com/forum/forums/air-suspension-pros-and-cons

Volker.Berlin | 27 December 2011

Lyle, thanks for pointing to those articles. Interesting stuff indeed, particularly when you keep in mind the the Model S' underside is perfectly flat. Getting rid of the tail pipe is a considerable aerodynamic advantage.

ckessel, I intend to maximize range by adding air suspension and aero wheels to my Model S (the only options I am already decided on) -- regardless which battery pack I end up with. In highway driving, together they should add at least 10% increased range (my guesstimate, I am extremely curious to see actual numbers) for $3,000 combined (I am also curious to see German option prices). Based on the 230 mi battery, that's around $130 per 1 additional mile of range (or $100 when the calculation is based on the 300 mi battery). Compare that to $143 per additional mile of range by upgrading to the next bigger battery pack (assuming there is one, you cannot increase the range of the 300 mi battery that way), and you get good value (range) for the money.

Keep in mind that the range you buy with improved aerodynamics only pays off at high speeds. Improved aerodynamics help next to nothing to increase range in city driving, but then again, in the city you will easily achieve or exceed each battery pack's advertised range. Going around 95 mph is not unusual on German Autobahns, and at that speed range will significantly suffer (if you need to go further you always have the option to go slower, that is not forbidden not even in Germany ;-). Aero wheels and air suspension will help to alleviate the drop in range at high speeds. If you want, these features do not actually increase range, they merely mitigate range decrease at higher speeds, but whatever way you look at it, it is a net gain: Same range at higher speeds or increased range at lower (still highway) speeds.

I see two potential pitfalls with this approach: One is the look of the aero wheels, but looking at the Options & Pricing page I'm not worried. They are a bit unusual, but indistinguishable from any other wheels once the car is in motion. And even when sitting, they do not ruin the favorable exterior of the Model S, IMO. Some may disagree.

More importantly, I am worried about the longevity and maintenance cost of the air suspension. Other forum readers who had air suspension on their (non-Tesla) cars have mixed experiences in this regard (see the Pros and Cons thread linked above). I would love to see some signs from Tesla that reassure me that I won't regret my decision for air suspension later. Like, an extended warranty.

Robert.Boston | 27 December 2011

More info from Tesla on the air suspension would definitely help inform my decision. What is the minimum and maximum ground clearance with air suspension? And, what does the W/mile curve look like with and without the air suspension?

My interest in the air suspension comes as much in the controllable height upward. My mother-in-law has mobility issues, and the road into my summer place has rocks-and-ruts issues.

Larry Chanin | 27 December 2011

Yes, more information regarding the reliability/warranty of air suspension would be very helpful. I would also like to know whether it would tend to mitigate the harshness of performance tires.

We have a number of Olympic sized speed bumps that we have to travel over on a regular basis. I'm wondering how quickly you can manually raise the car while driving?

Larry

Discoducky | 27 December 2011

If the air suspension offers a better ride and/or performs better (handling around corners) by either keeping the car more level (I asked at the Oct event but couldn't get a good answer) then I'll spring for it!

Mycroft | 27 December 2011

Ducky, which base & options are you planning on going with so far?

mklcolvin | 27 December 2011

I'm looking at this since we have a really steep driveway, and I wouldn't want to get the underside of my new baby all scratched up! Anyone have experience with air suspensions and steep driveways with other makes?

Discoducky | 27 December 2011

@Mycroft, I'm going for 60KWh (unless TSLA hits $40 then i'll go for 85KWh Sport for unlimited miles and carbon fiber) White microfiber 19" all season and options are pano and tech (nothing else) = 65,250

@mklolvin, I have a tuned 03 MINI Cooper S and a steep driveway, must go slow when you hit the slope but I usually don't even touch the brush guard. However, speed bumps are different, as I do touch those more than I'd like, but again if you go slow no worries. If TM offers a 10 year on the suspension I will might be swayed. But there needs to be some other benefit other than it lowers at speed and raises for load. Maybe they can do the decreased drag calculation for us to show efficiency gains cuz with such a smooth bottom I don't think it will make much difference. The turbulence from ICE underbellies I get but the physics don't work out in my head for Model S. It's smooth and flat. The only thing they could do to decrease drag would be to put golf ball dimples on it (who wants the patent?)

http://www.physicsforums.com/showthread.php?t=417914

Mycroft | 27 December 2011

Looks good! Until the performance package was announced, that's probably the configuration I would have gone with. I might have skipped the tech package though. I wouldn't have added the air suspension.

Larry Chanin | 27 December 2011

@Discoducky
I'm going for 60KWh (unless TSLA hits $40 then i'll go for 85KWh Sport for unlimited miles and carbon fiber) White microfiber 19" all season and options are pano and tech (nothing else) = 65,250

According to the current Pricing and Options only Black Microfiber is offered.

Larry

Discoducky | 27 December 2011

Typo, the exterior will be no-charge white.

Should have read "...White with microfiber"....

Brian H | 28 December 2011

Disco;
Based on the 50¢ climb since the pricing announcement, I perdiks it will hit $40 in perzakly 138 days (May 14, 2012).

;)

mvbf | 28 December 2011

Not much to add here other than this feature and how well works could make or break whether I purchase the model s or wait for something else. I am really hoping to gain some ground clearance for the tough road condition days while still driving at a reasonable speed at least 30mph but hopefully 40 to 50. In terms of maintenance I know a small group of people who have had difficulties with Audis old air suspension but those same people who opted for audis new air suspension had no problems. So I am going to bank on that these systems have got more reliable over the years and Tesla is smart enough to implement them well.

ncn | 30 December 2011

I'm going to be using that "raising or lowering" on the tough-road-condition days myself. Boy oh boy do we get those, even when it's clear and dry out....

Volker.Berlin | 19 January 2012

From an email by Walter Franck (Tesla Motors?) to brianman, via:
http://www.teslamotorsclub.com/showthread.php/7338-Responses-to-NAIAS-qu...

Dynamics on how the active air suspense will handle when corning is to be announced, but I can expand upon the height levels. Manual Adjustments are as follows:

  • Normal height = 6”
  • High Level 1 = 0.90” taller; When the vehicle accelerates above 19 mph, the clearance adjusts back to Normal height.
  • High level 2 = 1.3” above Standard and can be used for ascending a steep driveway or fording deep snow. Clearance reverts to High Level 1 above 10 mph.
  • Low Level = 0.79” under Standard; Active Air Suspension will automatically lower the vehicle for highway driving to improve aerodynamics. Low Level is also accessible from the touchscreen for loading/unloading of passengers. When the vehicle begins driving the clearance adjusts back to Normal height.
  • The suspension will also self-level the car. For example if you load a lot of weight in the trunk the vehicle will remain level.
Volker.Berlin | 19 January 2012

Thus ground clearance can be varied from 13.2 cm to 18.5 cm, which is awesome. I can't see now how I could justify not getting air suspension. This adds a whole new level(!) of practical value (and, I hope, some substantial highway range) to the Model S. I am still looking for disappointments, but at this stage, the Model S truly seems to be "the only car you ever need" (Elon Musk), at least for me.

JohnQ | 19 January 2012

@VB Thanks for cross posting between TMC and this forum. Makes it easier to keep up with the news!

Waiting to hear what the impact of the air suspension is on highway range. That's likely the most important factor for my driving habits and will be the decision maker for me.

olanmills | 19 January 2012

Does anyone know if air suspension also includes springs suspension as well. The reason I'm asking is because if there is a failure in the air suspension (such as a large leak or compressor failure), does that make the car undriveable?

olanmills | 19 January 2012

Also, I have a question about keeping the car level during cornering. How beneficial is this really? Does it improve handling? At first though, it seems like this would improve comfort, but if the car is kept level while your turn, won't the feeling of sliding in your seat be more pronounced? That seems less comfortable to me.

Timo | 19 January 2012

[Car staying level] better handling: Yes. More traction to all four wheels, less likely to roll over. Seat sliding: Less than without. Only cornering causing sliding, not gravity + cornering. Think motorcycles.

Note that majority of this is achieved by very low center of gravity, not by suspension. Any lower and car would start to lean on curves like motorcycles. "self leveling" in V.B post probably just means it levels the car if it is not loaded evenly. I don't think it affects car leveling in cornering (much anyway).

nhurst | 19 January 2012

Timo - I don't follow your logic. It seems to me that the lower the center of gravity, the less roll. The less roll, the more sliding on the seat. The traction is more dependent upon suspension geometry, how well the tire geometry in relation to the road is maintained. Finally, the self levelling is more likely to affect pitch (front to back levelling) than roll (side to side levelling).

EdG | 19 January 2012

When you're curving left in a car with a higher center of gravity, the left side of the car is higher than the right, and you slide MORE than if the car stays level.

Brian H | 19 January 2012

About levelling when parked: What's level? Parallel to the road? Gravity level (could be impossible on even slight slopes)?

Brian H | 19 January 2012

EdG's right, of course. A car's natural lean is the opposite of a motorcyclist's turning lean. The bike rider must do that to keep the CoG's "vector" intersecting the road between the 2 wheels. The S's leveling will keep the car centered on the middle of the road, more or less, without yielding to the outward vector trying to tip it over.

Runar | 20 January 2012

Will it be possible to use the air suspensions to change tires more easily?

I know that Citroen DS with hydropneumatic suspensions, this can be done. Full height, put something beneat the car, lower it and change the tire.;-)

It might seem that the heigth difference on the air suspensions on the Models s might be to smal to use it this way?

Would be a lot easier to change from summer to winter tires not having to use a manual jack. ;-)

EdG | 20 January 2012

From "Low Level" (.79" below norm) to "High Level 2" (1.3" above norm) there will be only 2.09" difference between the lowest setting and the highest. We'd need a lot more than that to use this feature instead of an external jack.

xhawk1011 | 20 January 2012

is it not true that the ride with air suspension is superior, akin to the 'rolls royce ghost' according to a quote somewhere? that alone seems worth 1500$ to me.

BYT | 20 January 2012

@xhawk: I read that quote to but I think it was referring to how solid the ride was with the batteries loading up the entire base of the car as apposed to the air suspension in particular. If that is what they meant however, I would easily pay $1,500 for that feature just to get the same "effect" but just don't think that's what they meant.

olanmills | 22 January 2012

I'm curious if anyone can answer my other question about what happens if the air suspension is not working. Does that make the car un-drivable?

Mycroft | 22 January 2012

I don't know. But what if it did? If the steering goes out or the brakes fail or if the headlights fail at night or if the windshield wipers fail in a rainstorm, then the car becomes un-drivable.

stephen.kamichik | 22 January 2012

I guess it depends on what fails in the air suspension system. I think you should email your customer rep at TM about this. He will probably have to ask the engineers about this.

olanmills | 23 January 2012

@MyCroft, well basically it will affect my decision on whether or not I want to spend $1,500 on it.

Without the air suspension there are x things that can go worng with the car, things that will cost me time, opportunity, and money. With the air suspension, there's at least x+1 things that can go wrong. Given that it costs more money, I want to evaluate the risks vs. the benefits.

From what I understand, air suspension is more complicated than the standard suspension, and also in general, it's less reliable (requires more maintenence).

Mycroft | 24 January 2012

Of course it's more complicated and prone to problems. You have compressed air tanks and pumps. Sounds like an obvious decision for you.

My dad refused to pay extra for electric windows for exactly the same reason. Just one more thing to go wrong with the car.

Discoducky | 24 January 2012

As long as the warranty is better than the batteries, I'll get the air suspension.

The recent snow in the Pacific NW has convinced me.

Mycroft | 24 January 2012

Yep, with > 6" of snow, I couldn't even get my SLK to the first stop sign.

Sudre_ | 24 January 2012

I never did understand my dads, "....but it can break...", logic. Anything can break. Warrenty is the answer. If you are planning to keep the car after the warrenty period then I guess it's a reasonable argument. My dad has never had a car more than 5 years..... I should say, my mom has never had a car more than 2 years.... my dad gets my moms car when she gets bored with it.
I am on my 11th year with my fully loaded Saturn. It doesn't have air suspension but the only thing to break on it has been motortrain stuff.

brianman | 24 January 2012

"I never did understand my dads...logic"
"my dad gets my moms car when she gets bored with it."

I don't know your dad but I can make some guesses.

1. Older generation has more memories of the impact of events like depressions and so forth. Value, hidden costs, avoidable drama in finances, etc. come from those memories.
2. Older generation has a higher ratio of men as the bread winner. Reinforces 1.
3. The second quote. He has to deal with "fixing at home" or "fixing while driving" issues that crop up with the vehicle as it grows out of the "isn't it cute" phase when the diaper smell gets worse.
4. Car technology has improved. Some providers are focusing on making cars that last, some not. Of the ones that are, some are succeeding, some not.

olanmills | 24 January 2012

@Mycroft Yes, it's obviously more complicated. Hence, I am trying to learn about how great the benefits are and how reliable/unreliable the tech typically is. It's not just a straight, "more complicated/cost = do not want". Air suspension is not something I'm very familiar with. I mean, I knew about its existence before, but I've never had the option to have or not have it on a vehicle, so I never cared to learn anything about it before.

For instance, I want the pano roof. Clearly there is some greater risk of it requiring maintence costs during the life of the car compared to a normal roof. Clearly, there is some risk that the car will be unusable should something go wrong with it (for instance, if the roof is stuck open and it's raining). However, I think the benefits are so good, and the expected reliability issues small enough, that I am willing to accept the cost and risk for the benefits.

(BTW, off topic, but I think it's debateable whether or not the basic electric window is more complicated than the manual one)