Horrible sound, but the car is off...
 

Pulled into a store lot, turned car off an heard this horrible grinding and clanking sound coming from from front drivers side. It stopped after a few seconds then started back up. There is a strong plasticky smell in the cabin.

Oddly the problem is not there when I'm driving, no fluids leaking just this racket when the car is off and there are no warnings on the dash. Just left it at the dealer hoping for the best.

Anyone know what it could be. (2007 A8)

Maybe air compressor for suspension. Hope not as those are costly. Is any part of the front end sagging when you leave the car for an extended period of time, say overnight?

No change in suspension, ride height normal on all corners.

It's the WABCO ECAS (Electronically Controlled Air Suspension) compressor.

Hundreds of posts here on the D3 Thread. Also outlined in the Sticky at the top of the thread.

Repairing is possible or replace with a new unit.

Always specify Genuine WABCO; George Westinghouse would be proud!

Do you know how much for parts and labor, and how long before suspension problems kick in?

Hundred of miles perhaps at best, not thousands. Or at least something like that before it gets screwed up worse even if it still sort of drives.

You also actually don't know if it is just the compressor or also a leak. Keep watching ride height, especially overnight or longer. Too much compressor running and then the wearing out is often the symptom but not necessarily root problem in and of itself. But if it has had prior air struts replaced and some limping along the way, this could just be the delayed failure due to too much prior use/wear.

If it is not for that smell I would ask you if you are sure it is not parking brake calibrating.

His sound is coming from the front driver side, so it cannot be the parking brake calibrating, true ?

It's always prudent to assume it's possible someone is mistaken about the location of a sound. It's a very easy mistake to make at times, acoustics can be weird.

It certainly sounds like the compressor has failed. I would NOT drive the car until it has been repaired or replaced. The hot plastic smell is likely from the insulation on the wires melting due to excessive current draw.