The only time I hear the "marble" is when I am reversing out of a parking space. It literally sounds like a marble is rolling somewhere in the tire well. The problem is a nuisance and I worry that it is an indication of a larger problem. Secondly, I bought my Volvo because of their reputation for reliability and safety. After finding this site I have spent literally hours wondering what will go wrong with my car although nothing has. There are some squeaks and in my opinion the idle is louder and a bit rumbling for a luxury car than I think it should be. Should I be worried about countless repairs and a slim wallet? Are there stats on these cars that account for money spent per mile to run them. Thanks in advance.