AlveyA8

SOMETIMES after parking and getting out of my car i hear a very intensive sound coming from the back sounds like a motor cranking which leads me to believe the air compressor is doing some work but why? It happens infrequesntly but when it does it seems like something horrible is going to happen and then it stops. The height of the car is in automatic mode and I have been driving at well below 80 MPH for some time before I actually park it in my garage. Is this normal - what is it?

Audi0s

its probably just leveling everything out. It also can be the evap emissions system doing a leak test of the fuel tank, etc. It should every complete drive cycle.

BasicSlvr

Normal. Regular cycles--the brakes are self-adjusting. I think it's pretty cool.

Vercet

Well, I have an answer for you!

The A8 has an electromechanical parking brake applicator. When you park, you should (and ideally you do) push the brake pedal in to pre-load the brakes and pull the park brake on. The automated system will quickly use your pre-loading of the pedal to assist it in setting the park brake, on each of the rear wheels. If you forget to set the brake, as you get out and close the car it will do it automatically for you - the "whirrrr -click" you can hear, which should just happen once. If, as a lazy driver, you have never preloaded and set the parkbrake, after a number of years the system sometimes needs a few cycles to set the parking brake on one (or both) the rear wheels - you hear a "whirrl - clunk, whirrl clunk whirrl clunk" until it succeeds. If your car is doing this, to save a maintenance call/light, make sure you press the brake pedal and then pull the parking brake every time you park! :-)