I've had my A6 for a month or so now and I've noticed it makes some unusual noises after I've parked it, not for long, but maybe 45 seconds. First noise is a hiss from under the bonnnet which I suspect is aircon related. Coolant level is fine - it's not used a drop in 2000 miles or so, but when I switch it off there's a noticeable hiss from somewhere. Climate works perfectly.. Second noise only happens sometimes. It's from the rear of the car but I can't work this one out. It's very similar to noises a Hyperactively suspended Citroen I owned used to make. Sort of creak as if it is settling down for a good nights sleep. Doesn't sound like the exhausts cooling, more suspension related I imagine, but I don't have a clue what it might be. Anyone elses do this? Car drives perfectly, and passed the MOT today with no advisories. It's fsh and properly looked after but I always like to know what is causing the weird noises!