You never hear of the rear ones developing leaks. Seems like it's only the front air springs that have this issue. Sounds like OP has the adjustable suspension.

As I understand it, CPO doesn't cover shocks/struts, but this is a leaky spring [which they don't exclude].

I do see the rears develop leaks, more often than the fronts at that just by the higher number of vehicles equipped with rear air than 4 wheel air. Rubber is rubber and will age accordingly.

BMW uses terrible rubber. I can understand high durometer suspension bushings not lasting, but components like this and engine hoses should last the life of the vehicle.

Name one vehicle made that engine hoses last the lifetime...? Name one vehicle that uses airsprings that last a lifetime as well? Rubber is rubber and there is not a compound of rubber available yet that will not wear in the conditions of vehicle use as such.

If you find such a miracle rubber you will find a billionaire who came up with the compound.

Every Honda and Toyota out there, and we're talking about 20 year old cars. None of them use air-springs though, this is regarding engine hoses. I'll be reusing most of the rubber hoses when I swap in the engine in my 98 Prelude (cut a couple of them).

Would be interested to know the life of air-springs in commercial vehicles.

It always cracks me up when stuff like this is shocking to European car guys. :p: