German Car Zone

'The Ultimate Driving Machine'....This is a Question for ENI.

BMW live up to it's standards of Sheer Driving Pleasure. I just want to know WHY? BMW does not use an Adaptive Type AIR Suspension. For sure they use Adaptive Dampers, but why don't they use Air Springs on the F01 7er Front & Rear. They have Daynamic drive + Adaptive drive and surely Computer controlled Air type dampers (used by Audi, Merc etc.) Could not hamper handeling that much? Reading comparison tests the 750i F01 is only critisized due to it's ride comfort - in comfort mode!? So for a luxury Sport Sedan in this price bracket, surely BMW could have used AIR? Oh yes! Then there is the benefit of hight adjustment end Rolls-Royce make use of Air Suspension (They are part of BMW Group) So, the same parts bin/supplier...

As for the X5, the same applies - Q7,Touareg,Cayenne & ML + GL has Air Springs with hight adjustment....WHY NOT THE X5 + X6

If this question is for Eni, you might as well have sent a private message instead of this.

Hi Klier, I do not know all the 'clever' people. So anybody who can help me on this subject???

I don't claim to know anything about this subject, but I really do think a big part of NOT using airmatic is the unability to have a sporty ride.
If BMW has to choose between sporty yet comfortable or super confortable (airmatic), they choose the frirst option.

BMW refuse to use air springs because they have a relatively slow response time and the the weight of the air springs with its related components are too heavy. Notice how Mercedes replace the air springs for normal steel spring suspension for the SL65 Black Series. A better compromise is to use those magnetic dampers which have a much quicker response time, and they are not as heavy.

I'm very far from an engineer, so it's only an opinion, but all air suspensions I drove/could ride with were very comfortable, BUT did not give the same road-feel as a steel one. The car is somehow "floating", even the hard suspensions of a Cayenne with pneumatic dampers doesn't allow the same contact as with conventional springs.

This must be particularly true on front suspensions, where BMW chose to use steel dampers, surely not to compromize the road and steering feel of the car.

Whereas the rear axle has less influence on these factors, and it is very obviously the rear axle who takes the more benefits from these air suspensions due to the weight changes (number of passengers, luggages) and has the most influence on the comfort of the passengers, especially at the rear.

So, steel springs at the front for road feel, air springs at the back for comfort and charge adaptability. As far as ride height is concerned... Well this is useless to say the least unless you live in Amazonia.

Of course, with this, you can't achieve the comfort of the S-Class and its all-air adaptive suspensions, but it is not what BMW wanted to do and if you're that concerned with comfort, then you might want to switch to Benz .

For the X5-X6 I don't know, they really could benefit from air suspensions as it allows a more supple ride while limiting bodyroll. And the air-suspended Cayenne is no comfort-oriented SUV either... You will notice however that the "sportier" GTS does come with steel springs.

I have no idea why BMW are not using active air suspension in their cars.

I guess standard springs with active dumpers have some advantages (eg. costs, weight, etc) over the air "springs" ... And I guess active air springs are not in line with BMW sporty nature. Therefore they always scarify a bit of comfort for an additioanal sportiness. That's what BMW is about - in every segment. Even in 7er one.

Once some sort of full front & rear air suspension was offered on E53 X5 - incl. ride height regulation. Was it in sports pack or on "is" models exclusive - I don't recall. But the option was costly, and not very much demanded.

Still some BMW models (X5, X6, 5er touring, 7er etc) use self-leveling rear air suspension: which adjust the rear suspension height accordingly to the load on rear axle: For better comfort & handling.

I guess a full active air suspension is too comfort-biased & too unresponsive for a more sportier drive.

Otherwise ... BMW customers know what to expect from BMW. Harsher ride is a part of every BMW. Of course by every generation cars are more comfortable -due new suspension solutions, but I guess that can be done with other tech than air springs as well.

The standard SL models don't have air springs either. All SL models have ABC which is hydraulic based, totally different from Airmatic in other Benzes.


M

I think the answer to the question is self-explanatory. Air springs are for ride comfort mainly and can be tuned for sporty dynamics, but they aren't the best solution. They're most likely more expensive (they certainly are when it comes to replacing them) to produce and most importantly they don't provide the proper connected-to-the-road feeling that a sporty-biased vehicle needs to relay to the driver.

Air springs are perfect for luxury cars, but sporting machines not so much. Like others have pointed out when MB, Jaguar, Audi and others get down to business with making a sportier version of a base car with air springs, the air springs are ditched. That answers the question right there. A BMW goes for road feel and connected feeling primarily so air spring are out, at least on the front axle.


M

That is true, ActiveBodyControl can be fitted to steel springs as it uses lifters to mechanically block the bodyroll when needed (AFAIK).

Whereas the Airmatic is a full-air springs system, available with or without the ABC. The response time issue has been sorted out on Airmatic, especially the v2.0 of the W221 (which also harmonizes better with the ABC, with no comfort-loss if ABC is fitted).

However, this system is heavy, and mostly bring comfort-benefits. The Magnetic damping system (metal particles in the hydrualic fluid of the damper, that can be somewhat controlled by magnetism to make the whole stiffer) is far less efficient (comfortwise) but much lighter, which is why it is primilarly fitted on sports car like the Vette or R8.