Ahhh. A perfect exaggeration and the precise language that gives these cars the price point (which I'll touch upon later) that they are in.
The EAS (electronic air suspension) was dubbed by Jeremy Clarkson to be "ingenious engineering". It provides incredibly comfortable, capable rides and allows the car to act as rugged or luxuriously as requested by the owner at a given point in time. The system consists of three basic components:
- Compressor (pulls in air, compresses it, and passes it along)
- Valve block (responsible for taking compressed air and distributing it to the springs)
- Air springs (act like a shock and spring entirely using air compression)
The valve block and compressor have average life spans of roughly 75-125k miles. The springs will last roughly that long though they should be checked more routinely.
Now, what normally happens is somewhere towards the end of the lifespan of the springs (shown below), the rubber starts to get slight cracks or splinters and air will start slowly leaking out. As there is a ton of pressure, even a very small slit will lose air somewhat quickly. This will be obvious to an individual paying even a little bit of attention but to those who just get in and drive, they don't notice. As they drive more and more, the hole gets larger and larger to the point the car can no longer inflate the car up on the spring and it goes into limp mode. Then they take it in.
Now, depending on how long the leak has been building, they also run the problem of damaging the compressor. After all, the compressor is working it's ass off to continually inflate the spring as it loses air. Now, around this point, all four springs are probably close to their end anyway so the dealer will suggest replacing the springs (cost around 125 online but will run 200-300 at the dealer) and will suggest a new compressor 500) and valve block (1000). Then you have installation and this, while rather easy, is time consuming. So now you have a several thousand dollar repair.
That said, if you pay attention, replace the springs when they are going, and don't kill your compressor/valve block, it's not a big deal. The rear springs and compressor were replaced within the last 3 weeks and I'm going to put new springs on the front as they are maybe 80% through the life span... I'd rather take care of it now to not strain the other components.
But this is a perfect microcosm of why even the educated auto world hates these cars... they hear a horror story from someone who was told by a rich mom that a suspension cost 5 grand and they shy away for life..
Now, that doesn't mean that it won't have issues.. it will. But, as long as you tend to the major components (EAS being one of them) it's not bad.